The ICD-10-CM code for chronic kidney disease falls under category N18, with specific codes assigned by stage. The most commonly used codes range from N18.1 for stage 1 through N18.6 for end-stage renal disease (ESRD). Picking the right code depends on the patient’s kidney function, measured by estimated glomerular filtration rate (eGFR), and any coexisting conditions like diabetes or hypertension.
CKD Codes by Stage
Each CKD stage has its own code based on how much kidney function remains. Here’s the full breakdown:
- N18.1 — Stage 1, eGFR 90 or above (kidney damage present but function is normal or increased)
- N18.2 — Stage 2 (mild), eGFR 60–89
- N18.30 — Stage 3, unspecified
- N18.31 — Stage 3a (moderate), eGFR 45–59
- N18.32 — Stage 3b (moderate), eGFR 30–44
- N18.4 — Stage 4 (severe), eGFR 15–29
- N18.5 — Stage 5, eGFR below 15
- N18.6 — End-stage renal disease (ESRD)
- N18.9 — Chronic kidney disease, unspecified
The split between Stage 3a and 3b is a relatively newer distinction. If documentation specifies the substage, use N18.31 or N18.32 rather than the unspecified N18.30. When both a numbered CKD stage and ESRD are documented for the same patient, only N18.6 is assigned.
Why Stage Specificity Matters
Using N18.9 (unspecified CKD) is technically valid, but it creates problems. Research into electronic health records has found that N18.9 is the single most frequently recorded nephrology diagnosis, which means a large number of CKD patients are coded without any stage information. This limits risk stratification, makes it harder to track disease progression at a population level, and can affect whether protective medications are flagged as clinically appropriate.
For Medicare risk adjustment, CKD stages carry specific Hierarchical Condition Category (HCC) weights. Stage 3 maps to HCC 138, Stage 4 to HCC 137, and Stage 5/ESRD to HCC 136. These weights directly influence reimbursement in value-based care models. If a Stage 4 patient is coded as unspecified, the practice loses the HCC 137 credit entirely. The system also applies a clinical hierarchy: if a patient qualifies for both Stage 4 and Stage 3, only the higher-severity HCC 137 counts toward the risk score.
Coding CKD With Hypertension
ICD-10 assumes a causal relationship between hypertension and CKD whenever both conditions are present. Unlike hypertensive heart disease, where the provider must explicitly document a link, hypertensive kidney disease is presumed. This means a patient with both high blood pressure and CKD gets coded under the I12 category (hypertensive chronic kidney disease) rather than coding hypertension and CKD separately.
An additional N18 code is still required to specify the CKD stage. So a typical chart for a hypertensive patient with Stage 3b CKD would carry both I12.9 and N18.32. The one exception: if CKD developed first and hypertension came later as a secondary condition, the coding falls under secondary hypertension codes instead.
Coding CKD With Diabetes
Diabetes codes in ICD-10 are combination codes that bundle the type of diabetes, the affected body system, and the complication into a single code. For a Type 2 diabetes patient with CKD, you would assign E11.22 (Type 2 diabetes with diabetic chronic kidney disease) along with the appropriate N18 stage code. Type 1 diabetes uses E10.22, and other diabetes categories have their own parallel codes under E08, E09, and E13.
Sequencing between the diabetes code and the CKD code depends on the reason for the encounter. If the visit is primarily for diabetes management, the E11.22 leads. If the visit focuses on kidney function, the N18 code can be sequenced first. As many diabetes complication codes as necessary can be used in a single encounter to capture the full clinical picture.
ESRD and Transplant Status Codes
N18.6 is reserved for end-stage renal disease and applies to patients on chronic dialysis. When using N18.6, you should also assign Z99.2 to identify the patient’s dialysis-dependent status. If the patient has a functioning kidney transplant, Z94.0 (kidney transplant status) is added.
Patients with a kidney transplant can still carry a CKD stage code if their transplanted kidney has reduced function. The transplant status code (Z94.0) and the CKD stage code are not mutually exclusive. However, if complications arise specifically from the transplant itself, those fall under a different code set in the T86 category rather than the N18 codes.
For ESRD patients who also have diabetes or hypertension, the N18.6 code is listed after the appropriate combination code. A patient with Type 2 diabetes and ESRD on dialysis would carry E11.22, N18.6, and Z99.2 in that sequence.