1. Home
  2. ICD-10-CM Codes
  3. N00–N99
  4. N20-N23
  5. N21
  6. 2025 ICD-10-CM Code N21.0

2025 ICD-10-CM Diagnosis Code N21.0

Calculus in bladder

ICD-10-CM Code:
N21.0
ICD-10 Code for:
Calculus in bladder
Is Billable?
Yes - Valid for Submission
Chronic Condition Indicator: [1]
Not chronic
Code Navigator:

N21.0 is a billable diagnosis code used to specify a medical diagnosis of calculus in bladder. The code is valid during the current fiscal year for the submission of HIPAA-covered transactions from October 01, 2024 through September 30, 2025.

Code Classification

  • Diseases of the genitourinary system
    N00–N99
    • Urolithiasis
      N20-N23
      • Calculus of lower urinary tract
        N21

Approximate Synonyms

The following list of clinical terms are approximate synonyms, alternative descriptions, or common phrases that might be used by patients, healthcare providers, or medical coders to describe the same condition. These synonyms and related diagnosis terms are often used when searching for an ICD-10 code, especially when the exact medical terminology is unclear. Whether you're looking for lay terms, similar diagnosis names, or common language alternatives, this list can help guide you to the correct ICD-10 classification.

  • Calcium oxalate calculus of urinary bladder
  • Calcium oxalate urolithiasis
  • Calculus in diverticulum of urinary bladder
  • Calculus of lower urinary tract
  • Calculus of lower urinary tract
  • Calculus of lower urinary tract
  • Calculus of lower urinary tract
  • Calculus of lower urinary tract
  • Calculus of lower urinary tract
  • Calculus of lower urinary tract
  • Oxalate urinary bladder stone
  • Phosphate calculus of urinary bladder
  • Small calculus particles in urinary bladder
  • Uric acid calculus of urinary bladder
  • Uric acid urolithiasis
  • Urinary bladder stone

Clinical Classification

Clinical Classifications group individual ICD-10-CM diagnosis codes into broader, clinically meaningful categories. These categories help simplify complex data by organizing related conditions under common clinical themes.

They are especially useful for data analysis, reporting, and clinical decision-making. Even when diagnosis codes differ, similar conditions can be grouped together based on their clinical relevance. Each category is assigned a unique CCSR code that represents a specific clinical concept, often tied to a body system or medical specialty.

Calculus of urinary tract

CCSR Code: GEN005

Inpatient Default: Y - Yes, default inpatient assignment for principal diagnosis or first-listed diagnosis.

Outpatient Default: Y - Yes, default outpatient assignment for principal diagnosis or first-listed diagnosis.

Clinical Information

  • Calcium Oxalate Urolithiasis

    urolithiasis in which the composition of the stones is predominantly calcium oxalate.

  • Uric Acid Urolithiasis

    urolithiasis in which the composition of the stones is predominantly urate.

Tabular List of Diseases and Injuries

The following annotation back-references are applicable to this diagnosis code. The Tabular List of Diseases and Injuries is a list of ICD-10-CM codes, organized "head to toe" into chapters and sections with coding notes and guidance for inclusions, exclusions, descriptions and more.


Inclusion Terms

Inclusion Terms
These terms are the conditions for which that code is to be used. The terms may be synonyms of the code title, or, in the case of "other specified" codes, the terms are a list of the various conditions assigned to that code. The inclusion terms are not necessarily exhaustive. Additional terms found only in the Alphabetic Index may also be assigned to a code.
  • Calculus in diverticulum of bladder
  • Urinary bladder stone

Type 2 Excludes

Type 2 Excludes
A type 2 excludes note represents "Not included here". An excludes2 note indicates that the condition excluded is not part of the condition represented by the code, but a patient may have both conditions at the same time. When an Excludes2 note appears under a code, it is acceptable to use both the code and the excluded code together, when appropriate.
  • staghorn calculus N20.0

Index to Diseases and Injuries References

The following annotation back-references for this diagnosis code are found in the injuries and diseases index. The Index to Diseases and Injuries is an alphabetical listing of medical terms, with each term mapped to one or more ICD-10-CM code(s).

Convert N21.0 to ICD-9-CM

Below are the ICD-9 codes that most closely match this ICD-10 code, based on the General Equivalence Mappings (GEMs). This ICD-10 to ICD-9 crosswalk tool is helpful for coders who need to reference legacy diagnosis codes for audits, historical claims, or approximate code comparisons.

Blad diverticulum calcul

ICD-9-CM: 594.0

Approximate Flag - The approximate mapping means this ICD-10 code does not have an exact ICD-9 equivalent. The matched code is the closest available option, but it may not fully capture the original diagnosis or clinical intent.

View Conversion

Bladder calculus NEC

ICD-9-CM: 594.1

Approximate Flag - The approximate mapping means this ICD-10 code does not have an exact ICD-9 equivalent. The matched code is the closest available option, but it may not fully capture the original diagnosis or clinical intent.

View Conversion

Patient Education


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:

  • Cystitis - inflammation of the bladder, often from an infection
  • Urinary incontinence - loss of bladder control
  • Overactive bladder - a condition in which the bladder squeezes urine out at the wrong time
  • Interstitial cystitis - a chronic problem that causes bladder pain and frequent, urgent urination
  • Bladder cancer

Doctors diagnose bladder diseases using different tests. These include urine tests, x-rays, and an examination of the bladder wall with a scope called a cystoscope. Treatment depends on the cause of the problem. It may include medicines and, in severe cases, surgery.

NIH: National Institute of Diabetes and Digestive and Kidney Diseases


[Learn More in MedlinePlus]

Code History

  • FY 2024 - No Change, effective from 10/1/2023 through 9/30/2024
  • FY 2023 - No Change, effective from 10/1/2022 through 9/30/2023
  • FY 2022 - No Change, effective from 10/1/2021 through 9/30/2022
  • FY 2021 - No Change, effective from 10/1/2020 through 9/30/2021
  • FY 2020 - No Change, effective from 10/1/2019 through 9/30/2020
  • FY 2019 - No Change, effective from 10/1/2018 through 9/30/2019
  • FY 2018 - No Change, effective from 10/1/2017 through 9/30/2018
  • FY 2017 - No Change, effective from 10/1/2016 through 9/30/2017
  • FY 2016 - New Code, effective from 10/1/2015 through 9/30/2016. This was the first year ICD-10-CM was implemented into the HIPAA code set.

Footnotes

[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.