2026 ICD-10-CM Diagnosis Code N18.1Chronic kidney disease, stage 1

ICD-10-CM Codes›N00–N99›N17-N19›CKD

ICD-10-CM N18.1
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

N18.1 is a billable ICD-10-CM diagnosis code for chronic kidney disease, stage 1. 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. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Chronic kidney disease.

N18.1 does not risk-adjust for Medicare Advantage under the CMS-HCC V28 model. It still risk-adjusts in the ESRD (V21) category 139 for payment year 2026.

Code Identity

ICD-10-CM Code
N18.1
Billable Status
Yes — Valid for Submission
Code Describes
Chronic kidney disease, stage 1
Short Description
Chronic kidney disease, stage 1
Same as the full description in the CMS dataset.
Parent Code
N18
Chronic kidney disease (CKD)

Code Classification

ChapterN00–N99Diseases of the genitourinary system
SectionN17-N19Acute kidney failure and chronic kidney disease
CategoryCKDChronic kidney disease (N18)
This CodeN18.1Chronic kidney disease, stage 1

Medicare Risk Adjustment (HCC)Billing

N18.1 does not risk-adjust for Medicare Advantage under the CMS-HCC V28 model, but it maps to payment categories in the other CMS models shown below.

CMS-HCC V28 (Medicare Advantage Payment Model)
Not mapped
no payment category in the model that pays 100% of MA risk scores
Prior Model (CMS-HCC V24)
Not mapped under V24
this diagnosis newly risk-adjusts under the V28 model
Other CMS Models
ESRD (V21): HCC 139
ESRD V21 weights: 0.000 dialysis, 0.000 functioning graft
Part D (RxHCC)
Not mapped
N18.1 does not risk-adjust in the RxHCC prescription drug model

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 due to chronic kidney disease stage 1
  • Anemia in chronic kidney disease
  • Benign hypertensive heart disease
  • Benign hypertensive heart disease and chronic renal disease stage 1
  • Chronic kidney disease due to benign hypertension
  • Chronic kidney disease stage 1
  • Chronic kidney disease stage 1 due to benign hypertension
  • Chronic kidney disease stage 1 due to drug induced diabetes mellitus
  • Chronic kidney disease stage 1 due to hypertension
  • Chronic kidney disease stage 1 due to type 1 diabetes mellitus
  • Chronic kidney disease stage 1 due to type 2 diabetes mellitus
  • Disorder of kidney due to drug induced diabetes mellitus
  • Hypertensive heart AND chronic kidney disease stage 1
  • Malignant hypertensive chronic kidney disease
  • Malignant hypertensive chronic kidney disease stage 1
  • Malignant hypertensive renal disease
  • Nephropathy due to secondary diabetes mellitus

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR GEN003
Chronic kidney disease
Default principal diagnosis: inpatient Yes · outpatient Yes

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 N18.1 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
585.1 Chro kidney dis stage I
Exact Match The mapping is direct, with no qualifiers.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About N18.1Overview

What is the ICD-10 code for chronic kidney disease, stage 1?

The ICD-10-CM code for chronic kidney disease, stage 1 is N18.1 (sometimes written as N181). It is billable on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

Is N18.1 (Chronic kidney disease (CKD)) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report chronic kidney disease, stage 1 on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does N18.1 group to?

When chronic kidney disease, stage 1 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.

What is the ICD-9 equivalent of N18.1?

Under the General Equivalence Mappings, chronic kidney disease, stage 1 converts to ICD-9-CM 585.1 (chro kidney dis stage I). The mapping is a direct match.

Does N18.1 risk-adjust for Medicare Advantage payment?

Not for Medicare Advantage: N18.1 maps to no category in the CMS-HCC V28 model. It still risk-adjusts in the ESRD (V21) category 139 (Chronic Kidney Disease/Mild or Unspecified (Stages 1-2 or Unspecified)).