Renal Failure, CKD, Dialysis & AV Fistulas

🔍 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).

🗂️ Alternative Terminology

🩺 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

🧭 Differential Diagnosis

📋 Clinical Indicators

🦴 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.

💊 Medication Impact / Treatment

Key Medications and Coding Implications

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📘 ICD-10-CM Guidelines

Section I.C.14 — Diseases of the Genitourinary System (Kidney)

Guideline 14.a: Stages of Chronic Kidney Disease (CKD)

Per FY 2027 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. If both a stage of CKD and ESRD are documented, assign N18.6 only. 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 conventions in the Tabular List per FY 2027 Guidelines I.C.14.a.3:

• 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:

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) when dialysis dependence is documented. The Tabular instructional note at N18.6 directs use of an additional code to identify dialysis status (Z99.2). Under CMS-HCC v28, N18.6 maps to HCC 326; Z99.2 does not create HCC 328.
• For encounters involving dialysis access preparation or catheter fitting/adjustment, use Z49.01 (extracorporeal dialysis catheter) or Z49.02 (peritoneal dialysis catheter) as applicable; for dialysis adequacy testing, use Z49.31 (hemodialysis) or Z49.32 (peritoneal dialysis). Do not use Z49.01 merely to represent routine hemodialysis treatment unless extracorporeal dialysis catheter fitting, adjustment, removal, replacement, toilet, or cleansing is the reason for the encounter.
• Peritoneal dialysis catheter encounters: Z49.02; adequacy testing PD: Z49.32.
• Patient noncompliance with dialysis: Z91.151 or Z91.158 — important MEAT element supporting continued documentation of dialysis dependence.

🔢 ICD-10-CM Code Set (Tabular)

Acute Kidney Injury (AKI) — Category N17

Chronic Kidney Disease (CKD) — Category N18

Dialysis Status & Encounter Codes

Kidney Transplant

AV Fistula / Vascular Access Complications

Related Conditions & Complications

🔎 Indexing

When using the FY 2027 ICD-10-CM Alphabetic Index, use the following main term pathways:

🏥 CPT

Dialysis Services

Dialysis Access — Peritoneal

Central Venous Access (Hemodialysis Catheters)

AV Fistula Creation & Revision

Dialysis Circuit Interventions (Endovascular)

Kidney-Related Procedures

Renal Laboratory Codes

🧾 HCPCS

Erythropoiesis-Stimulating Agents (ESAs)

IV Iron Products

Vitamin D & Mineral Metabolism

Dialysis Equipment & Supplies

📚 AHA Coding Clinic

💰 HCC / Risk Adjustment

CMS-HCC v28 Mapping Table — Renal Conditions

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. HCC 326 (CKD Stage 5/ESRD) supersedes HCC 327 (CKD Stage 4), HCC 328 (CKD Stage 3B), and HCC 329 (CKD Stage 3 except 3B). A patient with N18.6 (ESRD) and N18.4 (CKD4) in the same record maps to the highest applicable renal category, HCC 326; N18.5 also maps to HCC 326; N18.4 maps to HCC 327; N18.32 maps to HCC 328; and N18.30/N18.31 map to HCC 329. 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.

✍️ CDI Query Templates

🧑‍⚕️ 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

🎓 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 FY 2027 ICD-10-CM (effective October 1, 2026). 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: October 2026 · Next scheduled review: April 2027