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 682 through 684. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Chronic kidney disease.

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

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.

External Cause of Injuries IndexGuidance

References for this code in the External Cause of Injuries Index.

    • Disease, diseased
      • kidney (functional) (pelvis)
        • chronic
          • stage 1

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

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 682, 683, 684, with relative weights from 0.6003 to 1.4810 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.

Footnotes

[1] Chronic - a chronic condition code indicates a condition lasting 12 months or longer and its effect on the patient based on one or both of the following criteria:

  • The condition results in the need for ongoing intervention with medical products,treatment, services, and special equipment
  • The condition places limitations on self-care, independent living, and social interactions.