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This Clinical Documentation Guide (CDG) is the master renal reference for CCO-credentialed coders, CDI specialists, and auditors. It provides comprehensive guidance on coding Acute Kidney Injury (AKI), Chronic Kidney Disease (CKD) stages 1–5/ESRD, dialysis dependence, AV fistula complications, kidney transplant, and all related conditions. Content reflects FY2026 ICD-10-CM guidelines (effective October 1, 2025 – September 30, 2026), CY2026 CPT, HCPCS, and CMS-HCC v28 risk adjustment weights.
1. Definition
Acute Kidney Injury (AKI) is a sudden, reversible (or potentially reversible) deterioration in renal function occurring over hours to days, resulting in the retention of nitrogenous waste products and dysregulation of fluid, electrolyte, and acid-base homeostasis. AKI is defined by the Kidney Disease: Improving Global Outcomes (KDIGO) 2012 Clinical Practice Guidelines as any of the following: an increase in serum creatinine ≥0.3 mg/dL within 48 hours, an increase in serum creatinine to ≥1.5× baseline within 7 days, or urine output <0.5 mL/kg/h for ≥6 hours.
Chronic Kidney Disease (CKD) is a progressive, irreversible condition characterized by structural or functional kidney abnormalities present for >3 months, as defined by KDIGO CKD guidelines. CKD is staged according to estimated glomerular filtration rate (eGFR) using the CKD-EPI equation and the degree of albuminuria. Stages range from G1 (eGFR ≥90 mL/min/1.73m²) with kidney damage markers, through G5 (eGFR <15 mL/min/1.73m²), and ultimately End-Stage Renal Disease (ESRD) requiring renal replacement therapy (RRT).
End-Stage Renal Disease (ESRD) is the final, permanent stage of CKD in which kidney function has deteriorated to the point where the kidneys can no longer maintain life without renal replacement therapy — hemodialysis (HD), peritoneal dialysis (PD), or kidney transplantation. In ICD-10-CM, ESRD is uniquely represented by N18.6 and must always be paired with Z99.2 (dependence on renal dialysis) when the patient is actively dialyzed, per ICD-10-CM Official Guidelines for Coding and Reporting, Section I.C.14.
Arteriovenous (AV) Fistula is a surgically created anastomosis between an artery and vein, typically in the forearm or upper arm, used as the preferred vascular access for hemodialysis. AV fistulas provide high flow rates, long-term patency, and lower infection risk compared to grafts or catheters. Complications include stenosis, thrombosis, steal syndrome, aneurysm, and infection, as described by the National Kidney Foundation (NKF).
Epidemiology & Public Health Impact
According to U.S. Renal Data System (USRDS) Annual Data Report 2023, approximately 37 million Americans (14.9% of U.S. adults) have CKD, the vast majority undiagnosed. Over 800,000 people in the U.S. live with ESRD, and roughly 135,000 patients initiate dialysis annually. CKD is the 9th leading cause of death in the United States and is a major driver of Medicare expenditure, accounting for over $125 billion in Medicare costs annually. AKI affects approximately 10–15% of all hospitalized patients and >50% of ICU patients, per StatPearls: Acute Kidney Injury (NCBI).
2. Alternative Terminology
| Formal / ICD-10-CM Name | Colloquial / Clinical / Lay Terms |
|---|---|
| Acute Kidney Injury (AKI) | Acute renal failure (ARF), acute renal insufficiency, acute kidney failure, prerenal azotemia (when prerenal), acute tubular necrosis (ATN — a subtype) |
| Chronic Kidney Disease (CKD) | Chronic renal failure (CRF), chronic renal insufficiency (CRI), chronic renal disease, renal impairment, kidney disease |
| End-Stage Renal Disease (ESRD) | End-stage kidney disease (ESKD), kidney failure on dialysis, dialysis-dependent renal failure, terminal renal failure |
| Hemodialysis | HD, dialysis, blood dialysis, in-center dialysis, home hemodialysis (HHD), nocturnal dialysis |
| Peritoneal Dialysis | PD, CAPD (continuous ambulatory peritoneal dialysis), CCPD (continuous cycling peritoneal dialysis), home peritoneal dialysis, belly dialysis |
| Arteriovenous Fistula | AV fistula, AVF, dialysis fistula, Brescia-Cimino fistula, arteriovenous access |
| Arteriovenous Graft | AV graft, AVG, bridge graft, synthetic fistula, PTFE graft |
| Acute Tubular Necrosis | ATN, ischemic ATN, nephrotoxic ATN, intrinsic renal failure, intrinsic AKI |
| Glomerulonephritis | GN, nephritis, inflamed kidneys, nephrotic vs nephritic syndrome |
| Diabetic Nephropathy / CKD | Diabetic kidney disease (DKD), diabetic glomerulosclerosis, diabetic CKD, Kimmelstiel-Wilson disease |
| Hypertensive Nephropathy / CKD | HTN-related CKD, hypertensive renal disease, hypertensive nephrosclerosis |
| Renal Replacement Therapy | RRT, kidney replacement therapy, dialysis, transplant |
| Anemia of CKD | Renal anemia, anemia of chronic kidney disease, erythropoietin deficiency anemia |
| Hyperkalemia (in CKD) | High potassium, elevated K+, hyperpotassemia |
3. Signs & Symptoms
Acute Kidney Injury Signs & Symptoms
- Oliguria — urine output <400 mL/24h (most sensitive indicator of significant AKI)
- Anuria — urine output <100 mL/24h (suggests severe obstruction, cortical necrosis, or bilateral vascular occlusion)
- Rising creatinine/BUN — elevation from baseline (by KDIGO staging criteria)
- Fluid overload — edema, hypertension, pulmonary congestion, weight gain
- Electrolyte disturbances — hyperkalemia (most dangerous: cardiac arrhythmias), hyperphosphatemia, hyponatremia, metabolic acidosis
- Uremic symptoms — nausea, vomiting, altered mental status, asterixis (uremic flap), pericardial friction rub (uremic pericarditis)
- Hematuria — may suggest intrinsic causes (GN, ATN with pigmented casts)
- Proteinuria/casts — muddy brown granular casts (ATN), RBC casts (GN), WBC casts (pyelonephritis/AIN)
Chronic Kidney Disease Signs & Symptoms
- Early CKD (Stages 1–3) — often asymptomatic; detected via routine urinalysis, eGFR calculation, or microalbuminuria screening
- Moderate CKD (Stage 3–4) — fatigue, nocturia, mild edema, hypertension (frequently present), mild anemia (D63.1), decreased appetite
- Advanced CKD/ESRD (Stage 5) — severe fatigue, dyspnea, peripheral edema, uremic pruritus, metallic taste, cognitive impairment, restless leg syndrome, bone disease (renal osteodystrophy), secondary hyperparathyroidism
- Cardiovascular — accelerated atherosclerosis, LV hypertrophy, pericarditis, arrhythmias (hyperkalemia-driven)
- Hematologic — normochromic, normocytic anemia due to EPO deficiency; platelet dysfunction; increased bleeding tendency
- Dermatologic — uremic frost (severe, late finding), sallow complexion, calciphylaxis (vascular calcification with skin necrosis)
- Musculoskeletal — renal osteodystrophy (osteitis fibrosa cystica, osteomalacia), secondary hyperparathyroidism, gout/pseudogout (hyperuricemia)
AV Fistula Complication Signs & Symptoms
- Stenosis — reduced thrill/bruit, prolonged bleeding post-needling, high venous pressure during HD, inadequate dialysis (Kt/V)
- Thrombosis — absent thrill/bruit, swelling proximal to access, failure to dialyze adequately
- Steal syndrome — hand pain, pallor, paresthesias, weakness distal to access; worsens during HD
- Infection — erythema, warmth, tenderness, purulent discharge at access site; fever, bacteremia/septicemia
- Aneurysm/pseudoaneurysm — pulsatile bulging at access site; rupture risk
Symptoms alone (oliguria, edema, rising creatinine) do not drive a code. The physician/provider must document the diagnosis — “AKI,” “acute tubular necrosis,” “CKD stage 4,” etc. Coders should query when clinical indicators are present but the diagnosis is not explicitly stated in the record, per AHA Coding Clinic guidance.
4. Differential Diagnosis
| Condition | Key Distinguishing Features | Primary ICD-10-CM Code(s) |
|---|---|---|
| Prerenal AKI | BUN:Cr ratio >20:1; FENa <1%; responds to fluids; no casts; causes: dehydration, hemorrhage, heart failure (cardiorenal syndrome), hepatorenal syndrome, medications (NSAIDs, ACEi/ARBs) | N17.9; K76.7 (hepatorenal) |
| Intrinsic AKI — ATN | Most common intrinsic cause; muddy brown granular casts; FENa >2%; caused by ischemia (hypotension, sepsis) or nephrotoxins (aminoglycosides, contrast, myoglobin) | N17.0 |
| Intrinsic AKI — AIN (Acute Interstitial Nephritis) | Classic triad: fever, rash, eosinophilia; drug-induced (antibiotics, NSAIDs, PPIs); WBC casts; eosinophiluria (variable) | N10 (tubulo-interstitial nephritis, acute); N12 |
| Intrinsic AKI — Glomerulonephritis | RBC casts, proteinuria, hematuria; hypertension; may have systemic features (SLE, vasculitis, anti-GBM) | N00–N07 series; M32.14 (lupus) |
| Postrenal AKI (Obstruction) | Post-void residual >300 mL; hydronephrosis on US; BPH, ureteral stones, pelvic malignancy; rapidly reverses with relief of obstruction | N13.0–N13.6 (obstructive uropathy); N20.0–N20.1 (urolithiasis); N40.1 (BPH with LUTS) |
| AKI on CKD | Acute rise superimposed on known CKD baseline; code both AKI (N17.x) AND CKD stage (N18.x) | N17.x + N18.x (both required) |
| CKD Stage 3 vs 4 vs 5 | Requires eGFR documentation; provider must specify stage; eGFR alone insufficient without clinician attestation of stage | N18.30–N18.5 |
| Diabetic CKD vs Other Etiology CKD | Must have documented DM + CKD; ICD-10-CM presumes causal relationship — use E11.22 + N18.x (not I10 + N18.x when DM is the cause) | E11.22 + N18.x |
| Hypertensive CKD vs Other Etiology | Guidelines I.C.9.a.2 presume causal relationship between HTN and CKD; use I12.x combination codes even without explicit documentation of causation | I12.9 or I12.0 + N18.x |
| Contrast-Induced Nephropathy (CIN) | AKI within 24–72 hours of iodinated contrast administration; rising Cr without other cause; risk factors: pre-existing CKD, diabetes, heart failure, dehydration | N14.4 (nephropathy induced by drugs/toxins) + T50.8X5A (adverse effect of diagnostic radiopharmaceutical) |
| Rhabdomyolysis-Induced AKI | Elevated CK (>1000 U/L); tea-colored urine (myoglobinuria); positive urine dipstick blood without RBCs; causes: trauma, statin toxicity, alcohol, extreme exertion | M62.82 (rhabdomyolysis) + N17.0 (ATN) |
| Cardiorenal Syndrome | AKI/CKD worsening in setting of cardiac dysfunction (types I–V); complex bidirectional interaction; documented by cardiologist or nephrologist | N17.9 (AKI component) + I50.x (HF component) |
5. Clinical Indicators for Coders/CDI
| Clinical Indicator | Significance for Coding/CDI | Action Required |
|---|---|---|
| eGFR <60 mL/min/1.73m² for >3 months | Supports CKD Stage 3 or higher (HCC-qualifying N18.30+) | Query for CKD stage if not documented; never assign CKD stage from lab value alone |
| eGFR <30 mL/min/1.73m² | Consistent with CKD Stage 4 (HCC 326); high-value capture | Query provider: “Does the patient have CKD Stage 4 (eGFR 15–29)?” |
| eGFR <15 mL/min/1.73m² without dialysis | Consistent with CKD Stage 5 (HCC 327, highest non-dialysis HCC weight) | Query for N18.5 and reason RRT not initiated |
| Active hemodialysis or peritoneal dialysis | Requires N18.6 (ESRD) + Z99.2 (dialysis dependence) — both are needed for HCC 328 | Ensure both codes captured; Z99.2 alone does not trigger HCC 328 without N18.6 |
| Serum creatinine rising from known baseline | May indicate AKI (KDIGO criteria); does not auto-assign AKI without provider attestation | Query if creatinine ≥1.5× baseline: “Does this represent acute kidney injury?” |
| Oliguria/anuria noted in nursing or physician notes | Clinical indicator for AKI; urine output <0.5 mL/kg/h ≥6 h = KDIGO Stage 1 AKI | Query provider for diagnosis and etiology of AKI |
| Initiation of CRRT, hemodialysis, or peritoneal dialysis during hospitalization | Meets KDIGO AKI Stage 3 criteria regardless of creatinine; significant complication/comorbidity (MCC) | Query for AKI Stage 3 and underlying etiology; document initiation of RRT |
| Diabetes + CKD documented separately | ICD-10-CM presumes causal relationship; must use E11.22 + N18.x, never I10 alone | Alert provider/query to confirm diabetic CKD; use combination code E11.22 |
| HTN + CKD documented separately (without DM) | ICD-10-CM Section I.C.9.a.2 presumes causal relationship — use I12.x + N18.x | Ensure I12.x (not I10) is sequenced; confirm eGFR stage from provider |
| Documented dialysis noncompliance | Z91.15 supports MEAT documentation for dialysis-dependent patients | Capture Z91.15; document in CDI query response for clinical validity |
| Kidney transplant history | Z94.0 (transplant status, HCC 138 ~0.315 RAF); if complications present → T86.1x (rejection/failure) | Always capture Z94.0; query for rejection vs. failure vs. function decline (CKD of transplanted kidney N18.x) |
| Anemia treatment with EPO agents (Procrit, Aranesp) | Clinical indicator for anemia of CKD (D63.1); though D63.1 is no longer HCC v28, it supports complete documentation | Capture D63.1 + underlying CKD stage; EPO agent supports medical necessity |
| AV fistula creation, revision, or thrombectomy in H&P/OR report | T82.43x, T82.858A, T82.868A; CPT 36818–36833, 36901–36909 for dialysis circuit interventions | Confirm laterality; query complication type (stenosis, thrombosis, infection) |
CKD Stage Capture at Every Encounter is Mandatory for HCC. CKD stages N18.30–N18.5 map to HCC 326 or 327. ESRD with Z99.2 maps to HCC 328 (highest renal HCC, ~0.436 RAF). Because HCC risk scores require annual documentation, failing to capture CKD stage at every encounter results in significant RAF loss. Under CMS-HCC v28, N18.1 and N18.2 do NOT map to any HCC — a critical difference from prior models. Confirm the eGFR trend supports stage reaffirmation.
6. Anatomy & Pathophysiology
Normal Kidney Anatomy
The kidneys are paired retroperitoneal organs, each weighing approximately 120–170g in adults. Each kidney contains approximately 1 million nephrons — the functional units responsible for filtration, reabsorption, and secretion. The nephron consists of the renal corpuscle (glomerulus + Bowman’s capsule), proximal convoluted tubule, loop of Henle, distal convoluted tubule, and collecting duct. The glomerulus filters approximately 180 liters of plasma per day, producing a filtrate that is subsequently concentrated to approximately 1–2 liters of urine. The kidneys regulate fluid balance, electrolyte homeostasis (sodium, potassium, phosphorus, calcium, bicarbonate), acid-base balance, blood pressure (via the renin-angiotensin-aldosterone system), erythropoiesis (via EPO production), and vitamin D activation (25-OH-D3 → 1,25-(OH)2-D3 in the proximal tubule), as reviewed in StatPearls: Kidney Anatomy (NCBI).
Pathophysiology of AKI
AKI is classified by etiology into three categories, per KDIGO AKI guidelines:
- Prerenal AKI: Reduced renal perfusion (hypovolemia, decreased cardiac output, renal vasoconstriction) without structural kidney damage. Reversible with restoration of perfusion. BUN:Cr ratio typically >20:1; FENa <1%.
- Intrinsic (Renal) AKI: Direct damage to kidney parenchyma. The most common form is acute tubular necrosis (ATN), caused by ischemic or nephrotoxic insults to the proximal tubule and thick ascending limb of the loop of Henle. Other forms include acute interstitial nephritis (AIN — drug or immune-mediated), acute glomerulonephritis (GN), and vascular causes (thrombotic microangiopathy, renal artery thrombosis).
- Postrenal AKI: Obstruction of urinary flow at any level (ureteral, bladder outlet, urethral). Causes include BPH, ureteral stones, pelvic malignancy, bilateral ureteral obstruction. Early relief of obstruction restores function; prolonged obstruction leads to permanent damage.
Pathophysiology of CKD Progression
CKD progression involves a common final pathway of glomerular hypertension, proteinuria-driven tubular injury, and interstitial fibrosis/tubular atrophy (IFTA) regardless of the initial insult. Key mechanisms include:
- Glomerulosclerosis: Progressive loss of functioning nephrons leads to hyperfiltration in remaining nephrons, promoting glomerular hypertension and scarring
- TGF-β pathway activation: Drives fibrogenesis, myofibroblast activation, and interstitial fibrosis — the histologic hallmark of CKD progression
- Renin-angiotensin-aldosterone system (RAAS) activation: Angiotensin II drives efferent vasoconstriction, intraglomerular hypertension, inflammation, and fibrosis; hence ACEi/ARBs are first-line renoprotective therapy
- Proteinuria-mediated tubular injury: Filtered proteins activate tubular cells to produce inflammatory mediators, exacerbating interstitial fibrosis
- Uremic toxin accumulation: As eGFR falls, urea, creatinine, phosphorus, potassium, organic anions, and protein-bound uremic toxins accumulate, driving systemic complications
Pathophysiology of ESRD & Dialysis
When eGFR falls below 10–15 mL/min/1.73m², uremia becomes life-threatening without renal replacement therapy. Hemodialysis clears uremic solutes via diffusion across a semi-permeable membrane using a dialysate solution. Peritoneal dialysis utilizes the peritoneal membrane as the filter, with dialysate instilled into the peritoneal cavity. Both modalities remove uremic toxins, correct fluid overload, and partially restore electrolyte and acid-base balance, but neither restores endocrine functions (EPO production, vitamin D activation) — hence the need for erythropoiesis-stimulating agents (ESAs) and active vitamin D supplementation, per UpToDate: Overview of CKD Management.
7. Medication Impact / Treatment
Key Medications and Coding Implications
| Drug / Drug Class | Role in CKD/AKI | Coding Impact |
|---|---|---|
| ACE Inhibitors / ARBs (enalapril, losartan) | First-line renoprotection; reduce proteinuria; slow CKD progression in DKD and hypertensive CKD | Overdose or adverse effect can cause AKI (N14.4 + T36-T50 adverse effect code); long-term use supports chronic disease documentation |
| NSAIDs (ibuprofen, naproxen, ketorolac) | Reduce prostaglandin-mediated afferent arteriolar dilation; cause prerenal or intrinsic AKI, especially with baseline CKD | NSAID-induced AKI: N14.4 + T39.x5A (adverse effect of non-opioid analgesic) |
| Aminoglycoside antibiotics (gentamicin, tobramycin) | Direct proximal tubular toxicity; dose-dependent nephrotoxic ATN | ATN due to aminoglycosides: N17.0 + T36.5x5A (adverse effect) |
| Iodinated contrast agents | Contrast-induced nephropathy (CIN/CA-AKI); osmotic injury + direct tubular toxicity | N14.4 + T50.8X5A; note CIN risk assessment critical for pre-procedure documentation |
| Erythropoiesis-Stimulating Agents (ESAs): epoetin alfa (Procrit, Epogen), darbepoetin alfa (Aranesp), methoxy PEG-epoetin beta (Mircera) | Treat anemia of ESRD (D63.1); EPO deficiency is cardinal feature of CKD anemia | HCPCS Q4081 (epoetin ESRD), J0882 (darbepoetin ESRD); confirm D63.1 documented; ESA use without documented anemia = medical necessity risk |
| IV Iron (ferric carboxymaltose, iron sucrose, iron dextran, ferric gluconate) | Replenish iron stores depleted by HD blood losses and ESA-driven erythropoiesis | HCPCS J1439 (ferric carboxymaltose), J1756 (iron sucrose), J1750 (iron dextran), J2916 (ferric gluconate) |
| Paricalcitol (Zemplar) / Calcitriol | Active vitamin D analogs; treat secondary hyperparathyroidism, renal osteodystrophy | HCPCS J2501 (paricalcitol); supports documentation of secondary hyperparathyroidism (E21.1) in CKD |
| Phosphate binders (sevelamer, calcium carbonate, lanthanum carbonate, sucroferric oxyhydroxide) | Reduce hyperphosphatemia (E83.39) in CKD Stages 4–5/ESRD; prevent vascular calcification | Phosphate binder use supports E83.39 documentation; no specific HCPCS for oral agents in outpatient |
| Antihypertensives (diuretics, beta-blockers, CCBs, RAAS agents) | Control HTN in CKD; excessive diuresis can precipitate prerenal AKI | Adverse effects coded when causing AKI; documentation of HTN+CKD combination supports I12.x/I13.x |
| Tacrolimus / Cyclosporine / Mycophenolate (post-transplant immunosuppressants) | Prevent allograft rejection; calcineurin inhibitor nephrotoxicity can cause CKD of transplanted kidney | Long-term use Z79.02; tacrolimus toxicity causing AKI → N17.x + T45.1x5A (adverse effect) |
| SGLT2 Inhibitors (dapagliflozin/Farxiga, empagliflozin/Jardiance) | Now indicated for CKD with or without DM (FDA-approved for CKD renoprotection per FDA); reduce eGFR decline, AKI risk, and ESRD progression | Document DKD + SGLT2i use; supports medical necessity for diabetic CKD management |
| Bicarbonate supplementation | Treat metabolic acidosis (E87.2 acidosis) in CKD Stages 4–5; may slow progression | E87.2 (acidosis) should be coded when documented in CKD patients |
When ESAs (epoetin, darbepoetin) are ordered and the patient has documented CKD, query the provider: “Is the patient’s anemia attributable to CKD? If so, please document anemia in chronic kidney disease (D63.1) or specify an alternate etiology.” Even though D63.1 no longer carries an HCC weight in v28, it is essential for medical necessity and for documenting the underlying CKD stage that does carry HCC value.
Preview ends here. The full guide continues with FY2026 ICD-10-CM code sets, CPT surgical coding, MS-DRG mapping, reimbursement guidance, CDI query templates, and an audit checklist — all available to CCO Members.
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8. ICD-10-CM Guidelines (FY2026)
Section I.C.14 — Diseases of the Genitourinary System (Kidney)
Guideline 14.a: Stages of Chronic Kidney Disease (CKD)
Per FY2026 ICD-10-CM Official Guidelines, Section I.C.14.a, the stages of CKD are designated by the treating provider. The stage should be assigned based on the provider’s documentation of the specific stage. If the documentation indicates CKD without specification of stage, assign N18.9. If the documentation indicates “end-stage renal disease” (ESRD), assign N18.6 regardless of whether the exact eGFR is known. Do not infer CKD stage from laboratory values alone — provider attestation is required.
Guideline 14.a.1: Chronic Kidney Disease and Kidney Transplant Status
Patients who have undergone kidney transplant may still have some form of CKD because the kidney transplant may not fully restore kidney function. Therefore, the presence of CKD alone does not constitute a transplant complication. Assign the appropriate N18.x code for the patient’s stage of CKD, and code Z94.0 (Kidney transplant status), per Guidelines I.C.14.a.1. Code T86.1– for transplant complications only when the provider documents a complication such as transplant failure, rejection, or infection.
Guideline 14.a.2: Chronic Kidney Disease with Other Conditions
Patients with CKD may also suffer from other serious conditions such as diabetes mellitus and hypertension. The sequencing of the CKD code in relationship to codes for other contributing conditions is based on the circumstances of the admission/encounter per FY2026 Guidelines I.C.14.a.2:
- Diabetic CKD: See ICD-10-CM Section I.C.4 (Diabetes) — code E11.22 (Type 2 DM with diabetic CKD) as the diabetes combination code, followed by N18.x to identify the specific stage. Never use N18.x alone when DM is the cause, and never code I10 (HTN) or E11 separately when the combination code is available.
- Hypertensive CKD: See Section I.C.9.a.2 — assign the appropriate code from category I12 (HTN with CKD) to include both conditions. An assumed causal relationship is always coded even if the provider has not explicitly documented that the HTN caused the CKD. Add the N18.x code to identify the stage. NOTE: I12.0 = HTN with CKD Stage 5 or ESRD; I12.9 = HTN with CKD Stage 1–4 (or unspecified).
- HTN + Heart Disease + CKD: Use combination codes from category I13 (HTN HF + CKD). I13.0 = HTN HF with CKD Stages 1–4; I13.10 = HTN without HF with CKD stages 1–4 (unspecified); I13.11 = HTN without HF with CKD Stage 5/ESRD; I13.2 = HTN with HF and CKD Stage 5/ESRD.
KDIGO AKI Staging — Documentation Requirements
Per KDIGO AKI Guidelines, AKI staging is clinical; ICD-10-CM does not have separate codes for KDIGO stages. For coding purposes, the etiology drives code selection:
| KDIGO AKI Stage | Serum Creatinine Criteria | Urine Output Criteria | ICD-10-CM Note |
|---|---|---|---|
| Stage 1 | 1.5–1.9× baseline OR ≥0.3 mg/dL increase within 48h | <0.5 mL/kg/h for 6–12h | N17.9 (unspecified) if no specific cause documented; query for etiology |
| Stage 2 | 2.0–2.9× baseline | <0.5 mL/kg/h for ≥12h | N17.0 (ATN) if ischemic/nephrotoxic cause; N17.8 other; N17.9 unspecified |
| Stage 3 | ≥3.0× baseline OR ≥4.0 mg/dL OR initiation of RRT | <0.3 mL/kg/h for ≥24h OR anuria ≥12h | N17.x + document RRT initiation; highest MCC weight for DRG |
AKI on CKD — Sequencing
When AKI is documented in a patient with pre-existing CKD, assign codes for BOTH conditions — N17.x (AKI with etiology if known) and N18.x (CKD stage). The Tabular directs “Code also CKD” at N17. Sequencing follows the reason for the encounter: if AKI is the reason for the admission, sequence N17.x first; if the admission is for another condition and AKI is a complication, sequence per principal diagnosis rules, per AHA Coding Clinic guidance.
Dialysis Status — Key Guideline Rules
- For patients on dialysis, assign N18.6 (ESRD) AND Z99.2 (dependence on renal dialysis). Both codes are required per FY2026 Guidelines; N18.6 alone is insufficient to capture HCC 328.
- For encounter for dialysis as the reason for the visit, the primary code is Z49.01 (extracorporeal dialysis catheter fitting/adjustment) or Z49.31 (adequacy testing HD) — the disease code is secondary.
- Peritoneal dialysis catheter encounters: Z49.02; adequacy testing PD: Z49.32.
- Patient noncompliance with dialysis: Z91.15 — important MEAT element supporting continued documentation of dialysis dependence.
HTN + CKD Presumed Relationship: Many coders erroneously continue to code I10 (essential hypertension) separately when CKD is also present. Under ICD-10-CM Guidelines I.C.9.a.2, when both HTN and CKD are documented, presume a causal relationship and use I12.x (or I13.x if heart disease also present). Coding I10 + N18.x as separate conditions is a coding error in all but the rarest documented exceptions (e.g., provider explicitly states the CKD is not due to HTN).
9. ICD-10-CM Code Set (FY2026)
Acute Kidney Injury (AKI) — Category N17
| Code | Description | Notes / Coding Tips |
|---|---|---|
| N17.0 | Acute kidney failure with tubular necrosis (ATN) | Most common intrinsic AKI; caused by ischemia (sepsis, hypotension) or nephrotoxins (aminoglycosides, contrast, myoglobin). Code also causative substance/condition. MCC in DRG grouping. |
| N17.1 | Acute kidney failure with acute cortical necrosis | Rare; associated with obstetric catastrophes, septic shock, DIC. Bilateral cortical necrosis is irreversible. |
| N17.2 | Acute kidney failure with medullary (papillary) necrosis | Associated with sickle cell disease, NSAID abuse, diabetes with pyelonephritis, analgesic nephropathy. |
| N17.8 | Other acute kidney failure | Use when a specific type of AKI not covered by N17.0–N17.2 is documented (e.g., AIN-related AKI when the Tabular does not direct to a more specific code). |
| N17.9 | Acute kidney failure, unspecified | Default when provider documents “acute kidney injury” or “acute kidney failure” without specifying type. Query for etiology to assign more specific code. |
Chronic Kidney Disease (CKD) — Category N18
| Code | Description | HCC v28 | Notes |
|---|---|---|---|
| N18.1 | CKD Stage 1 (eGFR ≥90 with kidney damage markers) | No HCC | Requires documented markers of kidney damage (albuminuria, hematuria, imaging abnormality) in addition to eGFR ≥90. Often missed — confirm provider has documented “CKD Stage 1.” |
| N18.2 | CKD Stage 2 (eGFR 60–89 with kidney damage markers) | No HCC | Requires markers of kidney damage for >3 months. Many patients are under-staged; confirm actual stage from provider. |
| N18.30 | CKD Stage 3, unspecified | HCC 326 (Moderate CKD) ~0.200 RAF | Assign when provider documents “CKD Stage 3” without specifying 3a or 3b. Annual reaffirmation critical for HCC capture. |
| N18.31 | CKD Stage 3a (eGFR 45–59) | HCC 326 ~0.200 RAF | Documents initial moderate decline; query for 3a vs 3b when eGFR is in 45–59 range. |
| N18.32 | CKD Stage 3b (eGFR 30–44) | HCC 326 ~0.200 RAF | Higher risk of CKD progression and cardiovascular events than Stage 3a; important distinction for nephrology management. |
| N18.4 | CKD Stage 4 (eGFR 15–29) | HCC 326 ~0.200 RAF | High-priority capture; near-ESRD; referral to nephrology standard. MCC in inpatient DRG. |
| N18.5 | CKD Stage 5 (eGFR <15, not on dialysis) | HCC 327 (CKD Stage 5) ~0.320 RAF | Not yet requiring dialysis (or electing conservative management). Highest non-dialysis renal HCC. Confirm with provider that patient is NOT on dialysis. |
| N18.6 | End-Stage Renal Disease (ESRD) | Part of HCC 328 (with Z99.2) | Always pair with Z99.2 for HCC 328 (~0.436 RAF). Use when patient on chronic dialysis or has undergone successful kidney transplant and remains dialysis-dependent. NEVER code N18.5 + N18.6 together. |
| N18.9 | CKD, unspecified | No HCC | Use only when provider documents “CKD” or “renal failure, chronic” without specifying a stage. Query for stage — N18.9 carries no HCC weight and represents a missed opportunity. |
| N19 | Unspecified kidney failure | No HCC | Use sparingly — when neither AKI nor CKD is clearly documented. Excludes conditions classified to N17–N18. |
Dialysis Status & Encounter Codes
| Code | Description | Notes |
|---|---|---|
| Z99.2 | Dependence on renal dialysis | REQUIRED in addition to N18.6 for HCC 328. Code for every encounter for a dialysis patient. Includes HD and PD dependence. |
| Z49.01 | Encounter for fitting and adjustment of extracorporeal dialysis catheter | Use as primary code for HD catheter maintenance/access encounters. Code also N18.6 + Z99.2. |
| Z49.02 | Encounter for fitting and adjustment of peritoneal dialysis catheter | Use for PD catheter placement/adjustment encounters. Code also N18.6 + Z99.2. |
| Z49.31 | Adequacy testing for hemodialysis | Kt/V testing; use for outpatient encounters specifically for HD adequacy assessment. |
| Z49.32 | Adequacy testing for peritoneal dialysis | Peritoneal equilibration testing (PET); use for outpatient PD adequacy assessment encounters. |
| Z91.15 | Patient’s noncompliance with renal dialysis | Important MEAT element; supports continued documentation of dialysis dependence. Code also N18.6 + Z99.2 when applicable. |
Kidney Transplant
| Code | Description | Notes |
|---|---|---|
| Z94.0 | Kidney transplant status | HCC 138 (~0.315 RAF). Use for all encounters for transplant recipients without current complications. Code also N18.x if CKD of transplanted kidney is present. |
| T86.10 | Unspecified complication of kidney transplant | Use when complication documented but not further specified. Query for rejection vs. failure vs. infection. |
| T86.11 | Kidney transplant rejection | Immune-mediated destruction of allograft (hyperacute, acute, chronic). HCC 138 may apply + HCC 370. |
| T86.12 | Kidney transplant failure | Loss of allograft function; patient may require return to dialysis. Document whether patient returns to dialysis (add Z99.2 + N18.6). |
| T86.13 | Kidney transplant infection | Infectious complication of allograft (e.g., CMV nephritis, BK virus nephropathy). Code also infectious organism. |
| T86.19 | Other complication of kidney transplant | Includes calcineurin inhibitor nephrotoxicity, chronic allograft nephropathy not classified elsewhere. |
| Z48.22 | Encounter for aftercare following kidney transplant | Post-surgical follow-up; use as primary code for transplant aftercare visits. Not for ongoing CKD management visits. |
AV Fistula / Vascular Access Complications
| Code | Description | Notes |
|---|---|---|
| T82.43xA/D/S | Mechanical complication of arteriovenous fistula (initial/subsequent/sequela) | Mechanical complications: obstruction, displacement, malposition, perforation, protrusion. Use 7th character A (initial encounter), D (subsequent), S (sequela). |
| T82.7xxA/D/S | Infection and inflammatory reaction due to other cardiac and vascular devices, implants, and grafts | For AVF/AVG infection with or without bacteremia. Code also septicemia if present. Always add 7th character. |
| T82.858A | Stenosis of vascular grafts — initial encounter | Commonly applied to AVF stenosis limiting dialysis adequacy. Also applied to graft stenosis in HD access circuit. |
| T82.868A | Thrombosis of other cardiac and vascular devices, implants, and grafts — initial encounter | AVF/AVG thrombosis; requires intervention (thrombolysis, thrombectomy — CPT 36904/36905). Critical access complication. |
Related Conditions & Complications
| Code | Description | Notes |
|---|---|---|
| D63.1 | Anemia in chronic kidney disease | No HCC v28 (previously HCC 47 in v24 — major change). Always code underlying CKD stage. Supports medical necessity for ESA and IV iron therapy. |
| E87.5 | Hyperkalemia | Very common in CKD/ESRD; can be life-threatening (cardiac arrhythmias). MCC in inpatient DRG. Code when documented. |
| E83.39 | Other disorders of phosphorus metabolism (hyperphosphatemia) | Requires phosphate binder therapy; leads to vascular calcification and renal osteodystrophy in CKD. |
| E83.41 | Hypermagnesemia | Less common; caution with magnesium-containing antacids/laxatives in CKD. |
| E83.42 | Hypomagnesemia | Can occur with excessive dialysis removal or poor nutritional intake. |
| E87.1 | Hypo-osmolality and hyponatremia | Common in ESRD due to free water retention; may drive dialysis adjustments. |
| K76.7 | Hepatorenal syndrome | AKI in setting of advanced liver disease; prerenal physiology driven by splanchnic vasodilation. Query for HRS type 1 (AKI-HRS) vs. type 2 (CKD-HRS). Maps to liver HCC 27/28. |
| E11.22 | Type 2 DM with diabetic CKD | Combination code; always paired with N18.x for stage. HCC 37/38 (DM with complications). Never use E11 + N18.x without E11.22 when diabetic CKD is documented. |
| I12.0 | Hypertensive CKD with CKD Stage 5 or ESRD | Always add N18.5 or N18.6 + Z99.2. Combination code per Guidelines I.C.9.a.2. |
| I12.9 | Hypertensive CKD with CKD Stage 1–4 or unspecified | Add N18.1–N18.4 or N18.9 as applicable. Query for specific CKD stage. |
| I13.0 | HTN heart disease and CKD Stage 1–4 in heart failure | Triple combination: HTN + HF + CKD Stages 1–4. Add I50.x for HF type, N18.x for CKD stage. |
| I13.10 | HTN heart disease and CKD, without heart failure, CKD Stages 1–4 | HTN + CKD Stages 1–4 without documented HF; add N18.x. |
| I13.11 | HTN heart disease and CKD Stage 5 or ESRD without heart failure | Add N18.5 or N18.6 + Z99.2 as applicable. |
| I13.2 | HTN heart disease and CKD Stage 5 or ESRD with heart failure | Triple combination highest complexity; add I50.x (HF type), N18.5/N18.6 + Z99.2. Multiple HCC flags. |
| M10.xx | Gout | Common in CKD due to impaired uric acid excretion (hyperuricemia E79.0/274.9); gout with tophi has own specificity codes. Allopurinol dose reduction required in CKD. |
| N14.4 | Nephropathy induced by drugs, medicaments, or biological substances (unspecified) | Drug/toxin-induced AKI; always add external cause code (T-code) for the causative agent. |
AKI on CKD Dual-Coding Requirement: When the provider documents acute kidney injury superimposed on chronic kidney disease, ICD-10-CM requires codes for both conditions. Assign N17.x (with the most specific etiology available — ATN, cortical necrosis, etc.) AND the appropriate N18.x for the CKD stage. A note at N17 in the Tabular says “Code also CKD (N18.-).” Omitting either code is a documentation error that affects DRG grouping, risk adjustment, and quality metrics. See AHA Coding Clinic, Third Quarter 2013 for definitive guidance.
10. Indexing
When using the FY2026 ICD-10-CM Alphabetic Index, use the following main term pathways:
| Diagnostic Term | Index Path | Final Code |
|---|---|---|
| Acute kidney failure, tubular necrosis | Failure → kidney → acute → tubular → N17.0 | N17.0 |
| Acute kidney failure, unspecified | Failure → kidney → acute → N17.9 | N17.9 |
| CKD, Stage 3 | Disease → kidney → chronic → Stage 3 → N18.30 | N18.30 |
| CKD, Stage 3a | Disease → kidney → chronic → Stage 3a → N18.31 | N18.31 |
| CKD, Stage 4 | Disease → kidney → chronic → Stage 4 → N18.4 | N18.4 |
| ESRD | Disease → kidney → end-stage → N18.6 | N18.6 |
| Dialysis, renal dependence | Dependence → dialysis → renal → Z99.2 | Z99.2 |
| Diabetic CKD (T2DM) | Diabetes → type 2 → kidney complication → E11.22; then Stage: Disease → kidney → chronic → stage → N18.x | E11.22 + N18.x |
| Hypertensive CKD (stages 1–4) | Hypertension → kidney (renal) → Stage 1–4 → I12.9; then N18.x | I12.9 + N18.x |
| Hepatorenal syndrome | Syndrome → hepatorenal → K76.7 | K76.7 |
| Anemia in CKD | Anemia → chronic kidney disease → D63.1 | D63.1 |
| Thrombosis AV fistula | Complication → vascular device → thrombosis → T82.868A | T82.868A |
| Kidney transplant status | Status → transplant → kidney → Z94.0 | Z94.0 |
| Transplant rejection, kidney | Complication → transplant → kidney → rejection → T86.11 | T86.11 |
| Hyperkalemia | Hyperkalemia → E87.5 | E87.5 |
| Rhabdomyolysis | Rhabdomyolysis → M62.82 (then AKI N17.0 if documented) | M62.82 + N17.0 |
11. CPT (2026)
Dialysis Services
| CPT Code | Description | Global | Notes |
|---|---|---|---|
| 90935 | Hemodialysis procedure with single physician evaluation | XXX | Inpatient HD with one E&M evaluation same day. For routine uncomplicated HD in hospital setting. |
| 90937 | Hemodialysis procedure requiring repeated evaluation(s) | XXX | Use when HD requires more than one physician evaluation during the procedure (unstable patient, complications during run). |
| 90945 | Dialysis procedure other than hemodialysis with single physician evaluation | XXX | Covers peritoneal dialysis, hemofiltration, or other dialysis modalities. Inpatient PD. |
| 90947 | Dialysis procedure other than HD requiring repeated evaluations | XXX | Use when PD/other dialysis requires multiple evaluations due to complications. |
| 90951–90970 | ESRD services (monthly capitated codes, by age and number of face-to-face visits) | XXX | Monthly bundled payment for all ESRD-related physician services. Stratified by patient age (<2y, 2–11y, 12–19y, ≥20y) and number of face-to-face visits (1–4). Per CMS Physician Fee Schedule 2026. |
Dialysis Access — Peritoneal
| CPT Code | Description | Global | Notes |
|---|---|---|---|
| 49418 | Insertion of tunneled intraperitoneal catheter (Tenckhoff) — percutaneous | 10 days | Ultrasound-guided percutaneous placement of PD catheter. Image guidance separately reportable. |
| 49421 | Insertion of tunneled intraperitoneal catheter (Tenckhoff) — open | 10 days | Open surgical placement; used when percutaneous approach not feasible (prior abdominal surgery, adhesions). |
| 49422 | Removal of tunneled peritoneal dialysis catheter | 10 days | Used when transitioning from PD to HD, or removing infected/malfunctioning PD catheter. |
Central Venous Access (Hemodialysis Catheters)
| CPT Code | Description | Global | Notes |
|---|---|---|---|
| 36556 | Insertion of non-tunneled centrally inserted central venous catheter (≥5 years) | 0 days | Temporary HD catheter; acute access in hospital. |
| 36558 | Insertion of tunneled centrally inserted central venous catheter (≥5 years), without subcutaneous port or pump | 10 days | Long-term tunneled HD catheter (Permcath, Hickman-type). Standard for patients awaiting fistula maturation or not candidates for AVF. |
| 36578 | Replacement, tunneled CV catheter with subcutaneous port or pump, through same venous access | 0 days | Catheter exchange over guidewire. |
AV Fistula Creation & Revision
| CPT Code | Description | Global | Notes |
|---|---|---|---|
| 36818 | AV anastomosis, open; upper arm, cephalic vein transposition | 90 days | Basilic vein transposition to brachial artery; upper arm AVF creation. |
| 36819 | AV anastomosis, open; upper arm, basilic vein transposition | 90 days | Upper arm AVF with basilic vein transposition. High flow, good patency for obese patients or failed forearm access. |
| 36820 | AV anastomosis, open; forearm, vein transposition | 90 days | Radiocephalic (Brescia-Cimino) or forearm AVF creation; preferred first access per KDOQI guidelines. |
| 36821 | AV anastomosis, open; direct (Brescia-Cimino type) | 90 days | Classic radiocephalic AVF; first-choice vascular access. Direct side-to-side or end-to-side anastomosis. |
| 36825 | Creation of AV fistula by other than direct anastomosis — autogenous graft | 90 days | Prosthetic or venous graft interposition when direct anastomosis not feasible. |
| 36830 | Creation of AV fistula by other than direct anastomosis — non-autogenous graft (e.g., PTFE) | 90 days | PTFE (polytetrafluoroethylene) graft; higher infection and thrombosis risk than native AVF. |
| 36831 | Thrombectomy, open, AV fistula without revision | 90 days | Surgical thrombectomy of clotted AVF or AVG. |
| 36832 | Revision, open, AV fistula; without thrombectomy | 90 days | Surgical revision for aneurysm, pseudoaneurysm, stenosis, or maturation failure. |
| 36833 | Revision, open, AV fistula; with thrombectomy | 90 days | Combined surgical revision and thrombectomy. |
Dialysis Circuit Interventions (Endovascular)
| CPT Code | Description | Global | Notes |
|---|---|---|---|
| 36901 | Introduction of needle(s) and/or catheter(s), dialysis circuit, with diagnostic angiography of dialysis circuit | 0 days | Base code for dialysis circuit intervention; includes roadmap angiography. All add-ons below are reported in addition. |
| 36902 | 36901 + transluminal balloon angioplasty, peripheral dialysis segment | 0 days | Balloon dilation of stenosis in peripheral (venous outflow) segment. |
| 36903 | 36901 + transcatheter placement of intravascular stent, peripheral dialysis segment | 0 days | Stent placement for restenosis or elastic recoil in peripheral segment. |
| 36904 | Percutaneous transluminal mechanical thrombectomy and/or infusion for thrombolysis, dialysis circuit | 0 days | Endovascular thrombectomy/thrombolysis for clotted AVF/AVG. Does not include angioplasty (add +36905 or +36906). |
| 36905 | 36904 + angioplasty, peripheral dialysis segment | 0 days | Add-on: angioplasty after thrombectomy, peripheral segment. Bundle rules apply. |
| 36906 | 36904 + stent placement, peripheral dialysis segment | 0 days | Add-on: stent after thrombectomy, peripheral segment. |
| 36907 | Add-on: transluminal balloon angioplasty, central dialysis segment | ZZZ | Central venous stenosis (subclavian, SVC); always add-on to 36901–36906. |
| 36908 | Add-on: transcatheter stent placement, central dialysis segment | ZZZ | Central venous stent for central stenosis causing access dysfunction. |
| 36909 | Dialysis circuit permanent vascular embolization or occlusion | 0 days | Embolization of aneurysmal AVF or to redirect flow. Separate from angioplasty/stent codes. |
Kidney-Related Procedures
| CPT Code | Description | Global | Notes |
|---|---|---|---|
| 50200 | Renal biopsy — percutaneous, by trocar or needle | 0 days | Standard approach for native kidney biopsy; US guidance reported separately (76942). Essential for GN diagnosis, AIN, and unexplained CKD. |
| 50205 | Renal biopsy — by surgical exploration, with or without needle biopsy | 10 days | Open or laparoscopic surgical approach when percutaneous not feasible. |
| 50320 | Donor nephrectomy (including cold preservation); from living donor, open | 90 days | Living-donor kidney procurement; open approach. |
| 50323 | Donor nephrectomy from living donor, laparoscopic | 90 days | Minimally invasive living-donor nephrectomy; reduced donor morbidity. |
| 50327–50329 | Kidney transplant recipient procedures (50327 = bench surgery; 50328 = recipient nephrectomy; 50329 = transplantation) | 90 days | Full kidney transplant surgical package for recipient. Multiple codes may be reported for complex cases. |
| 50040 | Nephrostomy (renal drainage procedure) | 10 days | Percutaneous nephrostomy for obstructive uropathy causing AKI or to relieve pyonephrosis. |
Renal Laboratory Codes
| CPT Code | Description | Notes |
|---|---|---|
| 82565 | Creatinine, serum or plasma | Essential for eGFR calculation and AKI staging; must be trended against baseline. |
| 82570 | Creatinine, urine | Used for FENa calculation, protein:creatinine ratio; urine microalbumin monitoring. |
| 82043 | Microalbumin, urine (quantitative) | CKD staging requires kidney damage markers; microalbuminuria (>30 mg/g) is a key marker for CKD diagnosis and DKD progression monitoring. |
| 84520 | BUN (Blood Urea Nitrogen) | BUN:Cr ratio assists in distinguishing prerenal vs intrinsic AKI. Uremia threshold for dialysis initiation. |
| 84132 | Potassium, serum or plasma | Hyperkalemia (E87.5) monitoring; critical in CKD/ESRD for arrhythmia prevention. |
| 84100 | Phosphorus, serum or plasma | Hyperphosphatemia (E83.39) monitoring; drives CKD-MBD management. |
| 83615 | Lactate dehydrogenase (LDH) | Rhabdomyolysis workup; hemolysis assessment in ESRD patients. |
| 82728 | Ferritin, serum | Iron status monitoring for anemia of CKD management; target ferritin levels per KDIGO CKD-Anemia guidelines. |
| 83540 | Iron, serum | Part of iron panel for anemia of CKD/ESRD evaluation. |
| 83550 | Iron binding capacity (TIBC) | TSAT (transferrin saturation) = serum iron / TIBC × 100; target TSAT >20% for ESA initiation per KDIGO. |
| 81001 | Urinalysis, automated with microscopy | Urinary casts (muddy brown = ATN; RBC = GN; WBC = AIN/pyelo) guide etiology of intrinsic AKI. |
| 84155 | Protein, serum or plasma | Total protein; nutritional monitoring in dialysis patients; hypoalbuminemia common predictor of HD mortality. |
| 82040 | Albumin, serum or plasma | Dialysis adequacy surrogate; low albumin (<3.5 g/dL) = malnutrition/inflammation; strong mortality predictor in ESRD per USRDS. |
12. HCPCS (2026)
Erythropoiesis-Stimulating Agents (ESAs)
| HCPCS Code | Description | Typical Use / Notes |
|---|---|---|
| Q4081 | Injection, epoetin alfa, 100 units — for ESRD on dialysis | Epogen/Procrit in ESRD patients on hemodialysis. Bundled into ESRD PPS (per CMS ESRD PPS) for in-center HD patients. Requires documented D63.1 and N18.6 + Z99.2. |
| J0882 | Injection, darbepoetin alfa, 1 mcg — for ESRD on dialysis | Aranesp, ESRD patients on dialysis. Longer half-life allows weekly or biweekly dosing. |
| J0881 | Injection, darbepoetin alfa, 1 mcg — non-ESRD | Aranesp for pre-dialysis CKD anemia (D63.1 + N18.x not on dialysis) or cancer-related anemia. |
| J0885 | Injection, epoetin alfa, 1000 units — non-ESRD | Procrit/Epogen for pre-dialysis CKD anemia or chemotherapy-induced anemia. Different benefit category from Q4081. |
| J0887 | Injection, methoxy polyethylene glycol-epoetin beta, 1 mcg — ESRD | Mircera (CERA); monthly dosing for ESRD patients. Bundled in ESRD PPS. |
| J0888 | Injection, methoxy PEG-epoetin beta, 1 mcg — non-ESRD | Mircera for pre-dialysis CKD anemia management. |
IV Iron Products
| HCPCS Code | Description | Typical Use |
|---|---|---|
| J1439 | Injection, ferric carboxymaltose, 1 mg (Injectafer) | High-dose iron infusion; single-session repletion; outpatient IV iron for CKD and dialysis patients. |
| J1443 | Ferric pyrophosphate citrate powder, for addition to bicarbonate concentrate, 0.1 mg of iron (Triferic) | Added to dialysate solution for dialysis; provides microdose iron replacement during each HD session; unique delivery mechanism. |
| J1750 | Injection, iron dextran, 50 mg (INFeD, Dexferrum) | Older IV iron formulation; test dose required (anaphylaxis risk). Less preferred vs. newer formulations. |
| J1756 | Injection, iron sucrose, 1 mg (Venofer) | Most widely used IV iron in ESRD HD patients; safe, well-tolerated; typically 100–200 mg per HD session. |
| J2916 | Injection, sodium ferric gluconate complex, 12.5 mg (Ferrlecit) | IV iron for dialysis patients; administered as 125 mg infusion over 10 sessions typically. |
Vitamin D & Mineral Metabolism
| HCPCS Code | Description | Typical Use |
|---|---|---|
| J2501 | Injection, paricalcitol, 1 mcg (Zemplar) | Active vitamin D analog for secondary hyperparathyroidism (E21.1) in CKD Stages 3–5 and ESRD. Bundled in ESRD PPS for dialysis patients; separately billable for pre-dialysis CKD. |
Dialysis Equipment & Supplies
| HCPCS Range | Description | Typical Use |
|---|---|---|
| A4651–A4932 | Dialysis supplies (needles, bloodlines, gauze, tape, cleaning solutions, etc.) | Home hemodialysis supplies; billable to Medicare Part B for home HD patients. Not bundled in in-center PPS. |
| A4760 | Dialysate solution, any concentration | Dialysate for home peritoneal dialysis; Medicare Part B benefit. |
| A4765 | Dialysate concentrate, additives | Potassium chloride, calcium chloride additives for custom dialysate preparation. |
| E1510–E1699 | Dialysis equipment (hemodialysis machine, water system, conductivity meter) | Durable medical equipment for home hemodialysis. Prior authorization and proof of medical necessity required. |
| E1630–E1634 | Dialyzers (various membrane types and sizes) | High-flux vs. low-flux dialyzer; home HD supply. |
ESRD PPS Bundling: Under the CMS ESRD Prospective Payment System (PPS), the dialysis facility bundle covers all ESRD-related services during in-center dialysis sessions, including ESAs, IV iron, vitamin D analogs, and certain lab tests. For home dialysis patients, ESAs and IV iron are separately billable to Medicare Part B using the J-codes above. Understanding the PPS bundling rules is critical to avoid duplicate billing.
13. AHA Coding Clinic (Recent Guidance)
| Reference Period | Topic | Key Guidance Summary |
|---|---|---|
| AHA Coding Clinic, Q3 2013 | AKI on CKD dual coding | Confirmed that when AKI is superimposed on CKD, both N17.x and N18.x are required. The N17 Tabular note “Code also CKD (N18.-)” is an instructional note, not an excludes note, meaning both codes must be assigned simultaneously. (AHA Central Office) |
| AHA Coding Clinic, Q1 2016 | HTN + CKD presumed relationship | Reaffirmed that ICD-10-CM presumes a causal relationship between hypertension and CKD per Guidelines I.C.9.a.2. Even without explicit provider documentation of “hypertensive CKD,” when both HTN and CKD are documented in the same record, the coder uses I12.x or I13.x combination codes. No query to the provider is required for the presumed relationship (though the stage still requires provider documentation). |
| AHA Coding Clinic, Q2 2019 | CKD staging — provider documentation requirement | Clarified that CKD stage cannot be assigned based solely on laboratory eGFR values in the record. The provider must document the stage (e.g., “CKD Stage 3b”). If the provider documents only “CKD” without a stage, assign N18.9. CDI specialists should query to obtain specific stage documentation, especially when eGFR supports an HCC-qualifying stage (3 or higher). |
| AHA Coding Clinic, Q4 2020 | ESRD and Z99.2 co-coding | Clarified that for patients on chronic dialysis, both N18.6 (ESRD) and Z99.2 (dependence on renal dialysis) must be reported. Omitting Z99.2 when N18.6 is present (or vice versa) represents an incomplete code set. Both codes are needed to capture the full clinical picture and to trigger HCC 328 under CMS risk adjustment. |
| AHA Coding Clinic, Q2 2021 | Contrast-induced AKI (CIN) | Confirmed use of N14.4 for nephropathy induced by contrast agents. An external cause code from the T50.8 category (adverse effect of diagnostic agents) should be coded. Note: “Contrast-induced nephropathy” and “contrast-associated AKI” are increasingly distinct clinical terms — both map to N14.4 when documented by the provider. |
| AHA Coding Clinic, Q3 2022 | AV Fistula Thrombosis — Coding | Directed use of T82.868A for thrombosis of AV dialysis access (fistula or graft). When AV fistula thrombosis is treated with percutaneous mechanical thrombectomy, code T82.868A as the complication code, paired with CPT 36904 (or 36905/36906 if combined with angioplasty/stent). External cause 7th characters must be applied. |
| AHA Coding Clinic, Q1 2023 | Diabetic CKD — E11.22 + N18.x sequencing | Reinforced that E11.22 (Type 2 DM with diabetic CKD) is a combination code that represents both conditions. Assign N18.x as an additional code to identify the specific CKD stage. When diabetic CKD is the principal diagnosis driver, E11.22 sequences first followed by N18.x. Do not code E11.65 (DM with hyperglycemia) separately unless documented as a distinct current manifestation. |
| AHA Coding Clinic, Q2 2023 | SGLT2 inhibitors and renal protection documentation | Guidance on documenting SGLT2 inhibitor use for renal protection in CKD (with or without DM). Long-term use of SGLT2 inhibitor may be captured via Z79.899 (long-term use of other medication) when prescribed specifically for CKD renoprotection per FDA-approved indication. |
14. HCC / Risk Adjustment (v28)
CMS-HCC v28 Mapping Table — Renal Conditions
| ICD-10-CM Code(s) | Condition | CMS-HCC v28 Category | HCC # | Approx. RAF Weight |
|---|---|---|---|---|
| N18.6 + Z99.2 | ESRD on dialysis | Dialysis Status | HCC 328 | ~0.436 |
| N18.5 | CKD Stage 5 (not on dialysis) | Chronic Kidney Disease, Stage 5 | HCC 327 | ~0.320 |
| N18.30, N18.31, N18.32, N18.4 | CKD Stages 3–4 | Chronic Kidney Disease, Moderate (Stage 3/4) | HCC 326 | ~0.200 |
| N18.1, N18.2 | CKD Stages 1–2 | No HCC v28 | — | 0 |
| N18.9, N19 | CKD unspecified / Unspecified kidney failure | No HCC v28 | — | 0 |
| N17.0–N17.9 | Acute Kidney Injury (AKI) | No HCC v28 (alone) | — | 0 alone; pairs with underlying cause HCC |
| Z94.0 | Kidney transplant status | Organ Transplant Status: Kidney | HCC 138 | ~0.315 |
| T86.11, T86.12 | Kidney transplant rejection/failure | HCC 138 + HCC 370 (Major Organ Transplant Status) | HCC 138 + 370 | ~0.315 + additive |
| D63.1 | Anemia in CKD | No HCC v28 (was HCC 47 in v24 — major change) | — | 0 |
| E11.22 | Type 2 DM with diabetic CKD | Diabetes with Complications | HCC 37 or 38 | ~0.302 (HCC 37) |
| I12.0, I12.9, I13.x | HTN + CKD combinations | CKD HCC captured via N18.x; HTN HCC 224 if applicable | Via N18.x + HCC 224 | Additive |
| K76.7 | Hepatorenal syndrome | Chronic Liver Disease/Cirrhosis | HCC 27 or 28 | ~0.368 (HCC 27) |
| E87.5 | Hyperkalemia | No HCC v28 | — | 0 (but MCC inpatient) |
HCC 328 (Dialysis Status, ~0.436 RAF) is one of the highest-value HCCs in the renal family. It requires BOTH codes simultaneously:
- N18.6 (End-Stage Renal Disease) — the disease
- Z99.2 (Dependence on renal dialysis) — the treatment status
A common audit finding is that coders capture N18.6 alone, assuming it implies dialysis dependence. Per CMS-HCC v28 model documentation, both codes must appear in the data to trigger HCC 328. Annual documentation reaffirmation at every encounter is mandatory for risk-adjusted patients. Missing Z99.2 or N18.6 from a single year’s encounter data can result in HCC 328 dropping off the risk score entirely.
CKD HCC Hierarchy in v28
CMS-HCC v28 uses a hierarchical structure for CKD categories — higher stages supersede lower ones within the same disease family. A patient with N18.6 (ESRD) and N18.4 (CKD4) in the same record: only HCC 328 (ESRD/dialysis) counts. A patient with N18.5 alone counts as HCC 327. A patient with N18.30 counts as HCC 326. The hierarchy prevents double-counting but also means that coding specificity at the highest confirmed stage is essential — under-staging costs RAF weight. See CMS-HCC v28 Model Coefficients.
15. CDI Query Templates
Use when CKD is documented but no stage is specified, or when eGFR data suggests an HCC-qualifying stage (3–5/ESRD).
| Scenario | AHIMA/ACDIS-Compliant Query Wording (Multiple Choice) |
|---|---|
| CKD documented without stage; eGFR in 30–59 range | “The patient has a history of CKD documented in the chart. Based on the most recent eGFR of [value] mL/min/1.73m², please clarify the current CKD stage, if clinically appropriate: (a) CKD Stage 3a (eGFR 45–59); (b) CKD Stage 3b (eGFR 30–44); (c) CKD Stage 4 (eGFR 15–29); (d) Other/not applicable; (e) Unable to determine.” |
| ESRD but Z99.2 not documented; patient on dialysis per nursing notes | “Chart review indicates the patient is receiving [hemodialysis/peritoneal dialysis]. Please confirm whether the patient has end-stage renal disease (ESRD, N18.6) requiring ongoing renal replacement therapy: (a) Yes — ESRD, dependent on dialysis; (b) Yes — acute kidney injury with temporary dialysis (AKI, not ESRD); (c) Not applicable; (d) Unable to determine.” |
| AKI documented; etiology unclear | “The patient has documented acute kidney injury (AKI). To ensure accurate code assignment, please specify the most likely etiology: (a) Prerenal AKI (volume depletion, cardiorenal syndrome, hepatorenal syndrome); (b) Intrinsic AKI — Acute Tubular Necrosis (ischemic or nephrotoxic); (c) Intrinsic AKI — Acute Interstitial Nephritis (drug-induced or immune-mediated); (d) Postrenal AKI (obstruction); (e) AKI in the setting of CKD (AKI on CKD); (f) Other — please specify; (g) Unable to determine.” |
| Diabetic patient with CKD; combination code not documented | “The patient has documented Type 2 diabetes mellitus and chronic kidney disease. Is the CKD clinically attributable to the patient’s diabetes (diabetic nephropathy/diabetic CKD), or is there another primary etiology for the CKD? (a) Yes — diabetic CKD (diabetic nephropathy); (b) No — CKD is due to another cause (specify: ____________); (c) Both DM and [other cause] contributing; (d) Unable to determine.” |
| Kidney transplant patient with declining eGFR | “The patient has a history of kidney transplant (Z94.0). The recent eGFR of [value] represents a [decline/worsening] from prior values. Please clarify the current clinical status of the allograft: (a) CKD of transplanted kidney, Stage [specify]; (b) Kidney transplant rejection (acute/chronic); (c) Kidney transplant failure (returning to dialysis); (d) Other transplant complication — specify; (e) Stable — no complication; (f) Unable to determine.” |
| AV fistula with reduced thrill and elevated HD venous pressure | “Dialysis records indicate elevated venous pressures and/or reduced thrill/bruit noted on the patient’s AV fistula. Please document the current status of the dialysis access: (a) AV fistula stenosis; (b) AV fistula thrombosis; (c) AV fistula infection; (d) AV fistula aneurysm or pseudoaneurysm; (e) No complication — access functional; (f) Other — specify; (g) Unable to determine.” |
| HTN and CKD documented separately (coder using I10 + N18.x) | [Coder/CDI note — no query needed per Guidelines I.C.9.a.2]: Presume causal relationship and use I12.x + N18.x. Only query if provider has explicitly documented that the CKD is NOT due to HTN. Document the stage query separately if stage is unspecified. |
| Anemia in dialysis patient without D63.1 documentation | “The patient has documented CKD [Stage]/ESRD and is receiving [ESA/IV iron]. Please document the etiology of the patient’s anemia, if applicable: (a) Anemia due to CKD (anemia in chronic kidney disease); (b) Iron deficiency anemia; (c) Anemia due to [other cause — specify]; (d) Anemia not clinically significant at this time; (e) Unable to determine.” |
| Dialysis noncompliance noted in nursing/social work notes | “Chart documentation references missed dialysis sessions or patient refusal of dialysis. Please confirm and document, if clinically appropriate: (a) Patient noncompliance with renal dialysis (documented medical reason: ____________); (b) Intentional treatment refusal by patient; (c) Missed dialysis due to [logistic/medical reason not noncompliance]; (d) Not applicable; (e) Unable to determine.” |
16. Treatments (Clinical)
AKI Management
- Identify and reverse the underlying cause: Volume resuscitation for prerenal AKI; relief of obstruction for postrenal AKI; discontinuation of nephrotoxic agents
- Hemodynamic optimization: Maintain MAP >65 mmHg; vasopressors if needed in septic AKI; avoid excessive fluid administration once resuscitation achieved (liberal fluid strategy associated with worse outcomes per NEJM SMART Trial)
- Diuretics: Loop diuretics (furosemide) for fluid overload management; do not convert oliguric to non-oliguric AKI to improve outcomes
- Renal Replacement Therapy (RRT) initiation: Initiated for refractory hyperkalemia, metabolic acidosis (pH <7.1), volume overload unresponsive to diuretics, uremic encephalopathy/pericarditis, or oliguria/anuria with KDIGO Stage 3 AKI
- CRRT vs. intermittent HD: Continuous renal replacement therapy (CRRT) preferred in hemodynamically unstable ICU patients; KDIGO suggests no mortality difference vs. IHD in stable patients
CKD Management by Stage
- All stages: BP control (<130/80 for proteinuric CKD); ACEi or ARB for proteinuric CKD and DKD; dietary protein restriction 0.6–0.8 g/kg/day in CKD 4–5; smoking cessation; weight management
- Stage 3+: SGLT2 inhibitor (dapagliflozin, empagliflozin) for DKD or CKD with proteinuria per FDA CKD indication; finerenone (MRA) for DKD with elevated UACR; phosphorus restriction; bicarbonate supplementation for metabolic acidosis (serum bicarb <22 mEq/L); vitamin D deficiency treatment
- Stage 4–5: Nephrology referral mandatory; AV fistula creation planning (>6 months before anticipated dialysis need per KDOQI guidelines); erythropoiesis-stimulating agents when Hgb <10 g/dL and iron-replete; active vitamin D (paricalcitol) for secondary HPT (PTH >300 pg/mL)
- ESRD/Stage 5: Initiation of dialysis (eGFR <10–15, or symptomatic uremia); kidney transplant evaluation; peritoneal dialysis as equally efficacious alternative to HD; dietary potassium, phosphorus, and fluid restriction
AV Fistula Management
- Fistula surveillance: Monthly physical exam (thrill, bruit, arm examination); quarterly Kt/V adequacy testing; static venous pressure measurement at each HD session
- Stenosis treatment: Percutaneous transluminal angioplasty (PTA — CPT 36902) as first-line; stent placement (CPT 36903) for elastic recoil or recurrent stenosis
- Thrombosis treatment: Urgent percutaneous mechanical thrombectomy (CPT 36904–36906); surgical thrombectomy (CPT 36831) as alternative
- Infection treatment: AVF infection: IV antibiotics (gram-positive coverage: vancomycin + gram-negative for polymicrobial); AVG infection typically requires graft excision
- Maturation failure: 40% of new AVFs fail to mature adequately for cannulation; fistuloplasty (CPT 36902) or surgical revision (CPT 36832) may salvage failing fistulas
Dialysis Modalities
- In-center hemodialysis (ICHD): Three times weekly, 3–4 hours per session; dialysis facility setting; most common modality in U.S. (90% of ESRD patients per USRDS 2023)
- Home hemodialysis (HHD): More frequent sessions (5–6x/week or nocturnal); superior cardiovascular outcomes; requires motivated patient with caregiver; growing utilization
- Peritoneal dialysis (PD): CAPD or CCPD; home-based; preserves residual renal function; preferred for children, working-age patients, remote areas; peritonitis is primary complication
- Kidney transplantation: Gold standard for ESRD; best survival outcomes; requires lifelong immunosuppression; waitlist for deceased donor typically 3–5 years in U.S.; living donor preferred
17. Patient Education / Summary
Understanding Your Kidneys and Kidney Disease
Your kidneys are two fist-sized organs located in your back, just below your rib cage. Every day, they filter about 200 liters (roughly 50 gallons) of blood, removing waste products and extra water as urine. Healthy kidneys also control blood pressure, make a hormone that keeps red blood cells healthy (erythropoietin), and activate vitamin D to keep your bones strong, according to the National Kidney Foundation (NKF).
The Stages of Kidney Disease
Kidney disease progresses through stages based on how well your kidneys filter your blood — measured by a number called eGFR (estimated glomerular filtration rate). A healthy eGFR is 90 or above. As CKD progresses, the eGFR falls:
- Stage 1–2: Mild — kidneys work nearly normally, but there are signs of damage (protein in urine). Often no symptoms.
- Stage 3: Moderate — eGFR 30–59. Fatigue, mild swelling, and blood pressure changes may start. Treatment can slow progression significantly.
- Stage 4: Severe — eGFR 15–29. This is the time to prepare for dialysis or transplant. Work closely with your nephrologist.
- Stage 5/ESRD: Kidney failure — eGFR below 15. Dialysis or a kidney transplant is needed to survive.
Dialysis: What to Expect
Dialysis is a life-sustaining treatment that does the work your kidneys can no longer do. There are two main types:
- Hemodialysis (HD): Blood is cleaned outside your body using a machine with a special filter (dialyzer). Most people receive HD three times per week, about 4 hours per session, at a dialysis center or at home.
- Peritoneal dialysis (PD): A cleansing fluid is put into your belly through a soft tube (PD catheter). The lining of your belly (peritoneum) filters your blood naturally. Most PD is done at home, overnight while you sleep.
AV Fistula: Your Dialysis Lifeline
If you need hemodialysis, your doctor will create a vascular access — a way for blood to be drawn out, cleaned, and returned efficiently. The preferred access is an AV fistula: a small surgery that connects an artery and a vein in your arm. The connection makes the vein bigger and stronger so it can handle HD needles and high blood flow. It takes 6–12 weeks (sometimes longer) for the fistula to “mature” before it can be used. Take care of your fistula: check daily for a buzzing sensation (thrill), protect the arm from tight clothing or blood pressure cuffs, and report any pain, swelling, or loss of the thrill immediately, per NKF AV Fistula Guide.
Slowing Kidney Disease: What You Can Do
- Control your blood pressure — Target below 130/80 mmHg; take your blood pressure medications as prescribed
- Manage blood sugar — If you have diabetes, keeping A1C below 7% significantly slows CKD progression, per American Diabetes Association
- Follow a kidney-friendly diet — Reduce sodium, potassium (bananas, oranges, potatoes), phosphorus (processed foods, dairy, dark colas), and protein as directed by your dietitian
- Avoid nephrotoxic medications — NSAIDs (ibuprofen, naproxen) damage kidneys; always check with your doctor before taking over-the-counter pain relievers
- Stay hydrated — but not overhydrated — Fluid restrictions apply in later stages of CKD and for dialysis patients
- Attend all dialysis sessions — Missing dialysis is dangerous; it causes toxin and fluid buildup that can lead to heart problems and death
- Ask about transplant early — Getting evaluated for a kidney transplant before starting dialysis (pre-emptive transplant) leads to better outcomes. Contact your transplant center as soon as you reach Stage 4
For more information and support, visit the National Kidney Foundation (kidney.org) or the American Association of Kidney Patients (aakp.org).
About this Guide
This Clinical Documentation Guide is published by CCO Academy and is intended for credentialed coding, CDI, and clinical documentation professionals. Content is updated for FY2026 ICD-10-CM (effective October 1, 2025). All code assignments should be verified against the official ICD-10-CM Tabular List, AHA Coding Clinic, and applicable payer-specific policies. This guide does not constitute legal, medical, or compliance advice.
Last reviewed: April 2026 · Next scheduled review: October 2026 (FY2027 update)
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