Question 1

What is ICD-10 code N23?

Accepted Answer

N23 is the ICD-10-CM diagnosis code for unspecified renal colic. Severe pain in the side or back caused by a kidney stone when the specific type or location of the stone is not identified. N23 sits in the ICD-10-CM chapter for diseases of the genitourinary system (n00-n99), within the section covering urolithiasis (n20-n23).

N23 is a billable ICD-10-CM code but does not map to a payment HCC under the CMS-HCC V28, V24, ESRD, or RxHCC risk adjustment models. It can be reported on Medicare Advantage encounter data submissions but it does not contribute to a beneficiary's RAF score and therefore does not affect risk-adjusted payments to the plan.

Use this code only when stone composition and location are truly unknown.

Question 2

Is N23 an HCC code?

Accepted Answer

No. N23 is a billable ICD-10-CM code but does not map to any payment HCC category under the CMS-HCC V28, V24, ESRD, or RxHCC risk adjustment models. It can still be reported on Medicare Advantage encounter data submissions, but it does not contribute to the beneficiary's Risk Adjustment Factor (RAF) score and therefore does not affect the risk-adjusted capitation payment to the plan. V28 reached 100% phase-in for payment year 2026.

Question 3

Is N23 billable?

Accepted Answer

Yes. N23 is a billable ICD-10-CM code that can be reported on professional and institutional claims as a primary or secondary diagnosis when the provider documentation supports the specific condition described. Billable codes in ICD-10-CM are coded to the highest level of specificity available for the documented diagnosis. N23 is current for fiscal year 2026 and remains in the active CMS ICD-10-CM code set published by the National Center for Health Statistics.

Question 4

What is the V28 vs V24 difference for N23?

Accepted Answer

N23 does not map to a payment HCC under either the CMS-HCC V28 risk adjustment model or the older V24 model. V28 reached 100% phase-in for payment year 2026, replacing V24 which was used during the PY2024–PY2025 transition. Because neither model rewards N23 with a risk adjustment factor, it contributes zero to a Medicare Advantage beneficiary's RAF score in either version. Coders should check whether provider documentation supports a more specific child code that does map to a payment HCC.

Question 5

What should coders know when reporting N23?

Accepted Answer

Use this code only when stone composition and location are truly unknown If imaging confirms stone presence, use a more specific N20-N21 code instead

N23

Is N23 an HCC code?

What This Code Means

Coding Tips

Code Hierarchy

Open N23 in the Interactive Encoder