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Practice-Tier Clinical Tool

CKD Code Constructor

CKD coding is driven by comorbidities — check off what's documented and the correct ICD-10-CM combination assembles automatically, with HCC impact and sequencing guidance.

FY2027 update in progress. The FY2027 ICD-10-CM code set (effective 10/01/2026) is still loading, so a code may be missing or a deleted code may still show. Confirm against official CMS files before billing.

The 6-Axis CKD Coding Decision Framework

1 CKD Stage

Stage is always coded with N18.x as an additional code alongside any combination (I12/I13) code.

N18.1 Stage 1 — GFR ≥90, kidney damage markers
No HCC
N18.2 Stage 2 — GFR 60–89
No HCC
N18.31 Stage 3a — GFR 45–59
HCC 329 (v28)
N18.32 Stage 3b — GFR 30–44
HCC 329 (v28)
N18.4 Stage 4 — GFR 15–29
HCC 329 (v28)
N18.5 Stage 5 — GFR <15, not on dialysis
HCC 328 (v28)
N18.6 ESRD — Stage 5 + dialysis dependent
HCC 327 (v28)
N18.9 Unspecified
No HCC

⚠ Stage 5 ≠ ESRD. ESRD requires documented dialysis dependence — query if ambiguous.

2 Hypertension

ICD-10-CM presumes a causal relationship between HTN and CKD — you do not need explicit provider documentation of causation.

HTN + CKD (no HF) → Replace I10 with I12.9 (stages 1–4 or unspecified) or I12.0 (stage 5 / ESRD without HF)
HTN + CKD + Heart Failure → I12.x is replaced entirely by I13.x — never code both I12 and I13

Per Official Coding Guidelines I.C.9.a.2: The combination code (I12.x or I13.x) replaces I10 — do not code I10 separately when I12.x or I13.x is assigned. N18.x is always coded as an additional code to specify the CKD stage.

3 Heart Failure Type

Always specify HF type. Unspecified HF (I50.9) maps to HCC 226, but specifying systolic or diastolic upgrades capture to HCC 85 — a higher-weighted RAF category.

I50.21 Systolic HF, acute
I50.22 Systolic HF, chronic
I50.23 Systolic HF, acute-on-chronic
I50.31 Diastolic HF, acute
I50.32 Diastolic HF, chronic
I50.33 Diastolic HF, acute-on-chronic
I50.41 Combined systolic & diastolic, acute
I50.42 Combined systolic & diastolic, chronic
I50.43 Combined systolic & diastolic, acute-on-chronic
I50.9 HF unspecified — HCC 226 (specify type to capture HCC 85)
4 Diabetes Mellitus

When DM and CKD are both documented, ICD-10-CM assumes a causal link. Use diabetic chronic kidney disease combination codes — they replace a standalone N18.x.

Type 2 (most common)
E11.65 T2DM with hyperglycemia + CKD
E11.21 T2DM with diabetic nephropathy (no CKD stage documented)
E11.22 T2DM with diabetic chronic kidney disease + CKD stage
+ N18.x for stage
Type 1
E10.65 T1DM with hyperglycemia + CKD
E10.22 T1DM with diabetic chronic kidney disease
+ N18.x for stage
Other / Secondary DM
E13.22 Other DM with diabetic chronic kidney disease

⚠ DM + HTN + CKD: the I12.x HTN-CKD combination code is used alongside the E1x.22 diabetic chronic kidney disease code. Code all documented conditions.

5 Dialysis Status

Dialysis dependence always upgrades the stage to ESRD (N18.6) and requires Z99.2 regardless of how the CKD is otherwise documented.

N18.6 ESRD — always when dialysis-dependent
Z99.2 Dependence on renal dialysis — always add
Z49.01 Encounter for fitting of extracorporeal dialysis catheter
Z49.31 Encounter for adequacy testing for hemodialysis
⚡

When HTN + ESRD + HF: use I13.2 + N18.6 + I50.xx + Z99.2. This is the highest-complexity CKD combination — all four codes are required.

6 Kidney Transplant History

A transplant does not erase CKD — persistent CKD post-transplant is still coded. This is a common documentation gap.

Z94.0 Kidney transplant status (functioning)
+ N18.x still required if CKD persists
T86.10 Kidney transplant rejection, unspecified
T86.11 Kidney transplant failure
T86.12 Kidney transplant infection
N18.1–N18.5 CKD stage persists post-transplant
Note: ESRD (N18.6) is typically not coded after a functioning transplant

⚠ Guideline I.C.14: Code T86.1x complications when documented. Use Z94.0 only when the transplant is functioning without complication.

I12 vs. I13 — When to Use Which

Combination Code Use When Always Add HCC Impact
I12.9 HTN + CKD stage 1–4 or unspecified — no HF N18.1–N18.4, N18.9 HCC 136 (v28)
I12.0 HTN + CKD stage 5 or ESRD — no HF N18.5 or N18.6 + Z99.2 if ESRD HCC 134 (v28)
I13.0 HTN + CKD stage 1–4 or unspecified + Heart Failure I50.xx + N18.1–N18.4 HCC 85 + 136
I13.10 HTN + heart disease + CKD stage 1–4 — no HF N18.1–N18.4 HCC 136 (v28)
I13.11 HTN + heart disease + CKD stage 5 or ESRD — no HF N18.5 or N18.6 + Z99.2 HCC 134 (v28)
I13.2 HTN + ESRD + Heart Failure (any type) I50.xx + N18.6 + Z99.2 HCC 85 + 134

⚠ Key rule: I12.x and I13.x are mutually exclusive. Once heart failure is present alongside HTN + CKD, I12.x is replaced entirely by the appropriate I13.x code. Never code both categories for the same patient encounter.

Build My Code Set

Check off what's documented — your ICD-10-CM code combination and HCC guidance generate below.

Common CKD Coding Scenarios

Scenario 1: HTN + CKD Stage 3b

I12.9 Hypertensive CKD (1st-listed)
N18.32 CKD Stage 3b (additional)

Do not code I10 separately — I12.9 captures the HTN.

Scenario 2: HTN + CKD 4 + Systolic HF

I13.0 HTN CKD w/ heart failure (1st-listed)
I50.22 Systolic HF, chronic (additional)
N18.4 CKD Stage 4 (additional)

Scenario 3: Type 2 DM + CKD Stage 3a + HTN

E11.22 T2DM w/ diabetic chronic kidney disease (1st-listed)
I12.9 Hypertensive CKD (additional)
N18.31 CKD Stage 3a (additional) — HCC 329 (v28)

DM is sequenced first when DM is the reason for the encounter; otherwise sequence by reason for visit.

Scenario 4: ESRD + HTN + Diastolic HF on Dialysis

I13.2 HTN + ESRD + HF (1st-listed)
I50.32 Diastolic HF, chronic (additional)
N18.6 ESRD (additional)
Z99.2 Dependence on renal dialysis (additional)

CDI Opportunity: The Two Most Common CKD Documentation Gaps

1. I50.9 (HF unspecified) instead of systolic or diastolic — I50.9 maps to HCC 226, but specifying systolic (I50.22/I50.23), diastolic (I50.32/I50.33), or combined (I50.42/I50.43) upgrades capture to HCC 85 — a higher-weighted RAF category. A single documentation query can close this gap.

2. Stage 5 coded as ESRD without confirming dialysis — Documenting ESRD when the patient is not dialysis-dependent is incorrect. Always query for GFR and dialysis status when ESRD is documented without explicit dialysis mention.