Kidney Stone ICD-10 Codes: N20.0, N20.1, N20.2 and N20.9

The International Classification of Diseases (ICD) system provides a standardized way of classifying diseases, conditions and other health-related diagnoses. In the United States, ICD-10-CM (International Classification of Diseases, Tenth Revision, Clinical Modification) is used to report diagnoses for healthcare documentation, claims and other administrative purposes.

For kidney and ureteral stones, ICD-10-CM includes several codes within the N20 category. The specific code depends primarily on where the calculus is documented.

Kidney Stone ICD-10 Codes: Quick Reference

These codes describe urinary calculi based primarily on their documented location. The correct code should be selected according to the clinical documentation and the applicable ICD-10-CM coding guidelines.

ICD-10 vs. ICD-10-CM: What’s the Difference?

ICD-10 is an international classification system for diseases and other health conditions. ICD-10-CM is the U.S. clinical modification used for diagnosis coding.

This distinction is important because different countries may use their own national modifications of ICD-10. The kidney stone codes discussed on this page, including N20.0, N20.1 and N20.2, are ICD-10-CM codes used in the United States.

ICD-10-CM code sets are updated periodically. Healthcare professionals and medical coders should use the code set applicable to the date of service rather than relying on an older code list.

What Do N20.0, N20.1, N20.2 and N20.9 Mean?

N20.0 – Calculus of kidney

N20.0 refers to a calculus located in the kidney. Terms such as kidney stone, renal calculus and nephrolithiasis may be used in clinical documentation when appropriate.

N20.1 – Calculus of ureter

N20.1 refers to a calculus located in the ureter, the tube that carries urine from the kidney to the bladder.

N20.2 – Calculus of kidney with calculus of ureter

N20.2 is used when the documentation identifies calculus in both the kidney and ureter.

N20.9 – Urinary calculus, unspecified

N20.9 refers to urinary calculus when the available documentation does not specify the location sufficiently to assign a more specific N20 code.

The distinction between these codes is based primarily on the documented diagnosis and location of the calculus. The code itself does not describe every characteristic of the stone.

Kidney Stone vs. Renal Colic: Are They the Same ICD-10 Code?

No. A kidney stone and renal colic describe different things.

The N20 codes describe urinary calculi, including stones located in the kidney or ureter. N23 is the ICD-10-CM code for unspecified renal colic.

Renal colic refers to the severe, often intermittent pain that can occur when a urinary stone obstructs or irritates the urinary tract. A patient may therefore have a documented kidney or ureteral stone as well as renal colic.

The presence of pain alone does not establish which stone code should be used. Coding should reflect the diagnosis documented by the healthcare professional and the applicable coding rules.

What Does the ICD-10 Code Tell You—and What Does It Not Tell You?

An ICD-10-CM code provides a standardized classification of a diagnosis. It does not provide a complete description of a patient’s kidney stone.

For example, N20.0 identifies a calculus of the kidney, but the code itself does not tell you:

• How large the stone is
• Its exact position within the kidney
• What the stone is made of
• Whether it is likely to pass naturally
• Whether it is causing significant obstruction
• Whether the patient has an infection
• Whether a procedure is necessary

Those details may come from imaging reports, laboratory tests, clinical examination and other parts of the medical record.

The ICD-10 code therefore should not be used by itself to determine whether someone needs medication, observation, lithotripsy, ureteroscopy or another treatment. Treatment decisions depend on the patient’s symptoms, stone size and location, obstruction, infection, kidney function and other clinical factors.

What If a Kidney Stone Causes Obstruction or Hydronephrosis?

A urinary stone can obstruct the normal flow of urine. Depending on the location and severity of the obstruction, a patient may develop hydronephrosis or hydroureter.

These findings may require additional diagnosis codes when supported by the clinical documentation. For example, ICD-10-CM contains separate codes for certain forms of hydronephrosis and obstructive uropathy.

This means that a patient’s medical record may contain more than one relevant diagnosis. The stone itself, its location and associated complications may need to be documented separately according to the applicable coding rules.

A kidney stone code should therefore not be interpreted as a complete summary of all complications associated with the condition.

How Is the Correct Kidney Stone ICD-10 Code Determined?

The appropriate ICD-10-CM code is selected from the information documented in the patient’s medical record.

Relevant information may include:

• The location of the stone
• Whether the stone is in the kidney, ureter or both
• Other documented urinary calculi
• Associated obstruction or hydronephrosis
• Symptoms and diagnoses documented by the treating clinician
• Findings from imaging and other diagnostic tests
• The applicable ICD-10-CM coding guidelines

Imaging such as CT, ultrasound or X-ray may provide important information about the location and characteristics of a stone. However, diagnosis coding must follow the applicable coding rules and documentation requirements.

A code should not be selected simply because it appears to be the closest match to a patient’s symptoms.

How Accurate Coding Supports Kidney Stone Care

ICD-10-CM coding does not diagnose a kidney stone. Instead, it provides a standardized way of documenting a diagnosis that has already been established or documented by a healthcare professional.

Accurate coding can support healthcare in several ways.

Better medical documentation

A specific diagnosis code helps organize information in the medical record and distinguish a kidney or ureteral stone from other urinary conditions.

Claims and reimbursement

Diagnosis codes are used together with other information when healthcare services are submitted for billing and reimbursement.

Population health and research

Aggregated coded data can help healthcare organizations and researchers study patterns in kidney stones, healthcare utilization and associated conditions.

Continuity of care

Consistent documentation can help different healthcare professionals understand diagnoses recorded during previous encounters.

ICD-10-CM coding is therefore one component of the medical record. It does not replace clinical assessment, diagnostic imaging or treatment planning.

Other ICD-10-CM Codes Related to Urinary Stones

Not every urinary stone is coded within N20.

For example, ICD-10-CM separately includes codes for stones located in other parts of the urinary tract, including:

• N21.0 – Calculus in bladder
• N21.1 – Calculus in urethra
• N21.8 – Other lower urinary tract calculus
• N21.9 – Calculus of lower urinary tract, unspecified
• N23 – Unspecified renal colic

This distinction is useful because the location of a calculus affects which ICD-10-CM category may apply.

2026–2027 ICD-10-CM Updates

ICD-10-CM code sets are updated periodically. The Centers for Medicare & Medicaid Services (CMS) publishes the official code files and annual updates.

For the 2026 code year, CMS provides ICD-10-CM files applicable to encounters through September 30, 2026. CMS has also published the 2027 ICD-10-CM files, which apply to encounters from October 1, 2026 through September 30, 2027.

When using an ICD-10-CM code for billing, reporting or medical documentation, always verify that the code is valid for the applicable date of service.

Challenges and Limitations of Kidney Stone Coding

Coding errors and inconsistencies

Medical coding requires accurate clinical documentation. Errors can occur when the location of a stone or an associated condition is unclear or when outdated code references are used.

Limited information in an individual code

An ICD-10-CM code provides a standardized diagnostic label, but it does not capture every clinical detail about a kidney stone. Important information such as stone size, composition, degree of obstruction and imaging findings may need to be documented separately.

Differences between coding systems

ICD-10 is used internationally, but individual countries may use national modifications. Therefore, a code found in a U.S. ICD-10-CM reference should not automatically be assumed to apply to another country’s healthcare coding system.

Changes to code sets

ICD-10-CM codes and coding guidelines can change over time. Medical coders and healthcare organizations should verify codes against the code set applicable to the date of service.

Frequently Asked Questions About Kidney Stone ICD-10 Codes

What is the ICD-10-CM code for a kidney stone?

N20.0 is the ICD-10-CM code for calculus of kidney.

What is the ICD-10-CM code for a ureter stone?

N20.1 is the ICD-10-CM code for calculus of ureter.

What is N20.2?

N20.2 refers to calculus of the kidney with calculus of the ureter.

What is N20.9?

N20.9 refers to urinary calculus, unspecified.

What is the ICD-10-CM code for renal colic?

N23 is the code for unspecified renal colic.

Does an ICD-10 code tell me how serious my kidney stone is?

Not by itself. The code identifies the documented diagnosis, but factors such as stone size, location, obstruction, infection, kidney function and symptoms are needed to understand the clinical significance of a kidney stone.

Does N20.0 mean that I need surgery?

No. An ICD-10-CM code does not determine treatment. Treatment depends on the clinical characteristics of the stone and the patient’s overall condition.

Key Takeaway

The main ICD-10-CM codes for kidney and ureteral stones are N20.0, N20.1, N20.2 and N20.9. The appropriate code depends primarily on the documented location and diagnosis.

However, an ICD-10-CM code is not a substitute for the clinical information contained in imaging reports, laboratory results and medical records. Stone size, location, obstruction, infection and other clinical factors are important when determining the appropriate management of kidney stones.

Because ICD-10-CM code sets are updated periodically, healthcare professionals and medical coders should always verify the applicable code and coding guidelines for the relevant date of service.

References

1. Centers for Medicare & Medicaid Services (CMS), National Center for Health Statistics (NCHS). ICD-10-CM Official Guidelines for Coding and Reporting, FY 2026. U.S. Department of Health and Human Services; 2025.
   ICD-10-CM Official Guidelines for Coding and Reporting, FY 2026
2. National Center for Health Statistics (NCHS), Centers for Disease Control and Prevention (CDC). ICD-10-CM: International Classification of Diseases, Tenth Revision, Clinical Modification. Updated July 2, 2026.
   CDC ICD-10-CM Classification and Code Browser
3. Centers for Disease Control and Prevention (CDC), National Center for Health Statistics. ICD-10-CM Files: FY 2026 and FY 2027 Releases.
   Official ICD-10-CM Files and Annual Releases