2026 ICD-10-CM Diagnosis Code N18.4Chronic kidney disease, stage 4 (severe)
ICD-10-CM Codes›N00–N99›N17-N19›CKD
- Billable — Valid for Submission
- CC — Complication or Comorbidity
- Risk Adjusts — HCC 327
- Chronic Condition
N18.4 is a billable ICD-10-CM diagnosis code for chronic kidney disease, stage 4 (severe). It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 8, 19, 682 through 684. As a secondary diagnosis, it counts as a complication or comorbidity (CC) and moves an inpatient stay to a higher severity level within its MS-DRG family. It does not count, however, when the principal diagnosis is one of 299 closely related codes. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Chronic kidney disease.
For Medicare Advantage risk adjustment, N18.4 maps to CMS-HCC Category 327 (Chronic Kidney Disease, Severe (Stage 4)) under the V28 model, adding a risk factor of about 0.514 for a community, non-dual, aged beneficiary in payment year 2026.
Code Identity
Code Classification
Medicare Risk Adjustment (HCC)Billing
N18.4 maps to a payment category in the CMS-HCC model used to risk-adjust Medicare Advantage payments. Weights are the published community factors for payment year 2026.
Source: CMS Payment Year 2026 risk adjustment mappings and model software. Weights are relative factors, not dollar amounts; a beneficiary's total RAF also includes demographics and interactions. Browse all CMS-HCC categories.
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Anemia in chronic kidney disease
- Anemia in chronic kidney disease stage 4
- Benign hypertensive heart disease
- Benign hypertensive heart disease and chronic renal disease stage 4
- Chronic kidney disease due to benign hypertension
- Chronic kidney disease stage 4
- Chronic kidney disease stage 4 due to benign hypertension
- Chronic kidney disease stage 4 due to drug induced diabetes mellitus
- Chronic kidney disease stage 4 due to hypertension
- Chronic kidney disease stage 4 due to type 1 diabetes mellitus
- Chronic kidney disease stage 4 due to type 2 diabetes mellitus
- Disorder of kidney due to drug induced diabetes mellitus
- Hypertension in chronic kidney disease due to type 1 diabetes mellitus
- Hypertension in chronic kidney disease due to type 2 diabetes mellitus
- Hypertension in chronic kidney disease stage 4 due to type 1 diabetes mellitus
- Hypertension in chronic kidney disease stage 4 due to type 2 diabetes mellitus
- Hypertensive heart AND chronic kidney disease stage 4
- Malignant hypertensive chronic kidney disease
- Malignant hypertensive chronic kidney disease stage 4
- Malignant hypertensive heart disease
- Malignant hypertensive heart disease and chronic renal disease stage 4
- Malignant hypertensive renal disease
- Nephropathy due to secondary diabetes mellitus
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
Disease, diseased See Also: Syndrome;
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Patient EducationClinical
Chronic Kidney Disease
You have two kidneys, each about the size of your fist. Their main job is to filter your blood. They remove wastes and extra water, which become urine. They also keep the body's chemicals balanced, help control blood pressure, and make hormones.
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert N18.4 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About N18.4Overview
What is the ICD-10 code for chronic kidney disease, stage 4 (severe)?
The ICD-10-CM code for chronic kidney disease, stage 4 (severe) is N18.4 (sometimes written as N184). It is billable on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
Is N18.4 (Chronic kidney disease (CKD)) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report chronic kidney disease, stage 4 (severe) on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What MS-DRG does N18.4 group to?
When chronic kidney disease, stage 4 (severe) is the principal diagnosis on an inpatient stay, it groups to MS-DRG 8, 19, 682, 683, 684, with relative weights from 0.6003 to 6.6272 depending on complications. Higher weights mean higher Medicare reimbursement.
Is N18.4 a CC or MCC?
CMS lists N18.4 as a CC (complication or comorbidity) for FY 2026. Reported as a secondary diagnosis, it moves the inpatient stay to a higher-weighted DRG within its severity family. It does not count when the principal diagnosis is one of the 299 closely related codes in its exclusion list.
What is the ICD-9 equivalent of N18.4?
Under the General Equivalence Mappings, chronic kidney disease, stage 4 (severe) converts to ICD-9-CM 585.4 (chr kidney dis stage IV). The mapping is a direct match.
What HCC is N18.4?
N18.4 (chronic kidney disease, stage 4 (severe)) maps to CMS-HCC Category 327 (Chronic Kidney Disease, Severe (Stage 4)), commonly written as HCC 327, in the CMS-HCC V28 model used for Medicare Advantage risk adjustment in payment year 2026. It mapped to HCC 137 under the retired V24 model. It also maps in the PACE (CMS-HCC V22), ESRD (V21), and ESRD (V24) models. In the Part D prescription drug model it maps to RxHCC 263.
Does N18.4 risk-adjust for Medicare Advantage payment?
Yes. When documented and reported on a Medicare Advantage encounter, N18.4 adds a risk adjustment factor of about 0.514 to the beneficiary's RAF score for a community, non-dual, aged enrollee (published V28 weights range from 0.447 to 0.661 depending on the payment segment). A more severe related category (HCC 326) supersedes it when both are reported. See the full factor table on the HCC 327 category page.
