2026 ICD-10-CM Diagnosis Code N28.81Hypertrophy of kidney

ICD-10-CM Codes›N00–N99›N25-N29›N28

ICD-10-CM N28.81
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

N28.81 is a billable ICD-10-CM diagnosis code for hypertrophy of kidney. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 698 through 700. Coders also document this condition as compensatory hypertrophy of single kidney. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Other specified and unspecified diseases of kidney and ureters.

Code Identity

ICD-10-CM Code
N28.81
Billable Status
Yes — Valid for Submission
Code Describes
Hypertrophy of kidney
Short Description
Hypertrophy of kidney
Same as the full description in the CMS dataset.
Parent Code
N28.8
Other specified disorders of kidney and ureter

Code Classification

ChapterN00–N99Diseases of the genitourinary system
SectionN25-N29Other disorders of kidney and ureter
CategoryN28Other disorders of kidney and ureter, not elsewhere classified
This CodeN28.81Hypertrophy of kidney

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Compensatory hypertrophy of single kidney
  • Hypertrophy of kidney
  • Hypertrophy of left kidney co-occurrent and due to congenital hypoplasia of right kidney
  • Hypertrophy of right kidney co-occurrent and due to congenital hypoplasia of left kidney
  • Large kidney
  • Left renal hypoplasia
  • Right renal hypoplasia

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.

    • Hypertrophy, hypertrophic
      • kidney (compensatory)

Clinical ClassificationClinical

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

CCSR GEN006
Other specified and unspecified diseases of kidney and ureters
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Kidney Diseases

You have two kidneys, each about the size of your fist. They are near the middle of your back, just below the rib cage. Inside each kidney there are about a million tiny structures called nephrons. They filter your blood. They remove wastes and extra water, which become urine. The urine flows through tubes called ureters.

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert N28.81 to ICD-9-CMHistory

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

ICD-9-CM
593.1 Hypertrophy of kidney
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 N28.81Overview

Is N28.81 (Other specified disorders of kidney and ureter) a billable code?

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

What MS-DRG does N28.81 group to?

When hypertrophy of kidney is the principal diagnosis on an inpatient stay, it groups to MS-DRG 698, 699, 700, with relative weights from 0.6899 to 1.6544 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of N28.81?

Under the General Equivalence Mappings, hypertrophy of kidney converts to ICD-9-CM 593.1 (hypertrophy of kidney). 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.