2026 ICD-10-CM Diagnosis Code N21.9Calculus of lower urinary tract, unspecified
ICD-10-CM Codes›N00–N99›N20-N23›N21
- Billable — Valid for Submission
- Not Chronic
N21.9 is a billable ICD-10-CM diagnosis code for calculus of lower urinary tract, unspecified. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 693 through 694. Coders also document this condition as calculus of lower urinary tract. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Calculus of urinary tract.
Code Identity
Code Classification
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Calculus of lower urinary tract
Tabular List NotesGuidance
Coding notes and annotation back-references applicable to this code.
Type 1 Excludes
- calculus of urinary tract NOS N20.9
A type 1 excludes note is a pure excludes note. It means "NOT CODED HERE!" An Excludes1 note indicates that the code excluded should never be used at the same time as the code above the Excludes1 note. An Excludes1 is used when two conditions cannot occur together, such as a congenital form versus an acquired form of the same condition.
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
Stone (s) See Also: Calculus;
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Patient EducationClinical
Bladder Diseases
The bladder is a hollow organ in your lower abdomen that stores urine. Many conditions can affect your bladder. Some common ones are:
Read the full article at MedlinePlus
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Convert N21.9 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About N21.9Overview
What is the ICD-10 code for calculus of lower urinary tract, unspecified?
The ICD-10-CM code for calculus of lower urinary tract, unspecified is N21.9 (sometimes written as N219). It is billable on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
Is N21.9 (Calculus of lower urinary tract) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report calculus of lower urinary tract, unspecified on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What MS-DRG does N21.9 group to?
When calculus of lower urinary tract, unspecified is the principal diagnosis on an inpatient stay, it groups to MS-DRG 693, 694, with relative weights from 0.7817 to 1.3445 depending on complications. Higher weights mean higher Medicare reimbursement.
What is the ICD-9 equivalent of N21.9?
Under the General Equivalence Mappings, calculus of lower urinary tract, unspecified converts to ICD-9-CM 594.9 (lower urin calcul NOS). The mapping is a direct match.
