N21Header code — not billable

Calculus of lower urinary tract

Chapter
14. Diseases of the genitourinary system
Category
N21
Effective date
October 1, 2026

Related codes in category N21

N21.0Calculus in bladderYesN21.1Calculus in urethraYesN21.8Other lower urinary tract calculusYesN21.9Calculus of lower urinary tract, unspecifiedYes

Frequently asked questions

What is ICD-10 code N21?

N21 is an ICD-10-CM diagnosis code for Calculus of lower urinary tract.

Is N21 a billable code?

No. N21 is a category/header code, not billable on its own — use one of its more specific child codes instead.

What ICD-10-CM chapter is N21 in?

N21 falls under Chapter 14: Diseases of the genitourinary system.

When did N21 become effective?

N21 has been effective since October 1, 2026, per the CMS/CDC ICD-10-CM annual release.

What other codes are related to N21?

N21 belongs to category N21, which includes 4 other codes — see the related codes list on this page.

ICD-10-CM data maintained by CDC/CMS (public domain). Always verify codes with authoritative sources before making coding or billing decisions.