2026 ICD-10-CM Diagnosis Code N27Small kidney of unknown cause

ICD-10-CM Codes›N00–N99›N25-N29›N27

ICD-10-CM N27
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

N27 is a non-billable ICD-10-CM category code for small kidney of unknown cause, so it cannot be submitted on claims. Use a more specific code from this category instead, such as N27.0, N27.1, and N27.9.

Code Identity

ICD-10-CM Code
N27
Billable Status
No — Non-Billable Category
Code Describes
Small kidney of unknown cause
Chapter
N25-N29
Other disorders of kidney and ureter

Code Classification

ChapterN00–N99Diseases of the genitourinary system
SectionN25-N29Other disorders of kidney and ureter
CategoryN27Small kidney of unknown cause
This CodeN27Small kidney of unknown cause

Specific Coding for Small kidney of unknown causeOverview

Non-specific codes like N27 require more characters. Use one of these billable codes instead:

  • Use N27.0 for Small kidney, unilateral

  • Use N27.1 for Small kidney, bilateral

  • Use N27.9 for Small kidney, unspecified

Tabular List NotesGuidance

Coding notes and annotation back-references applicable to this code.

Includes

  • oligonephronia

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.

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 N27Overview

Is N27 (Small kidney of unknown cause) a billable code?

No. This is a category header that groups the codes for small kidney of unknown cause, and headers cannot be submitted on claims. Claims for small kidney of unknown cause need a more specific code from this category, such as N27.0, N27.1, and N27.9.