N27 ICD-10-CM Code: Small kidney of unknown cause
N27 is not a CMS-HCC payment code. MEAT criteria · RAF Calculator · HCC coding software
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FY 2026 Apr update / Diseases of the genitourinary system (N00-N99) / Other disorders of kidney and ureter (N25-N29)
N27
Header CodeICD-10-CMOfficial ICD-10-CMCodebook guidanceSmall kidney of unknown cause
CMS-HCC V28
N/A—
Not mapped
CMS-HCC V24
N/A—
Not mapped
ACA/HHS
N/A—
Not mapped
ESRD/PACE
N/A—
Not mapped
RXHCC
N/A—
Not mapped
Code Book Path
Inclusion Terms
OfficialNo inclusion terms are included in this display for N27. Check the code and parent instructions in the Code Book.
Excludes 2
Official- certain conditions originating in the perinatal period (P04-P96)Inherited from N00-N99, N25-N29
- certain infectious and parasitic diseases (A00-B99)Inherited from N00-N99, N25-N29
- complications of pregnancy, childbirth and the puerperium (O00-O9A)Inherited from N00-N99, N25-N29
- congenital malformations, deformations and chromosomal abnormalities (Q00-Q99)Inherited from N00-N99, N25-N29
- endocrine, nutritional and metabolic diseases (E00-E88)Inherited from N00-N99, N25-N29
- injury, poisoning and certain other consequences of external causes (S00-T88)Inherited from N00-N99, N25-N29
- neoplasms (C00-D49)Inherited from N00-N99, N25-N29
- symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)Inherited from N00-N99, N25-N29
- disorders of kidney and ureter with urolithiasis (N20-N23)Inherited from N00-N99, N25-N29
Related Codes
Includes
Official- oligonephronia
Excludes 1
OfficialNo Excludes 1 notes are included in this display for N27. Check the code and parent instructions in the Code Book.
Code First
OfficialNo Code First sequencing instructions are included in this display for N27. Check the code and parent instructions in the Code Book.
Use Additional
OfficialNo Use Additional Code instructions are included in this display for N27. Check the code and parent instructions in the Code Book.
Code Also
OfficialNo Code Also instructions are included in this display for N27. Check the code and parent instructions in the Code Book.
Current with CMS: FY2026 ICD-10-CM Apr 1 update (effective Apr 1 – Sep 30, 2026) · CMS-HCC V28, 100% phased in for payment year 2026. FY2027 code set already staged for October 1, 2026. How HCC Buddy stays current →
- Code
- N27
- Description
- Small kidney of unknown cause
- HCC (V28)
- No CMS-HCC V28 mapping
- RAF reference coefficient
- —
- Billable
- No
- Payment year
- 2026
Coder workflow notes
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What This Code Means
N27 is the ICD-10-CM diagnosis code for small kidney of unknown cause. N27 sits in the ICD-10-CM chapter for diseases of the genitourinary system (n00-n99), within the section covering other disorders of kidney and ureter (n25-n29).
Header codes like N27 cannot be reported on claims directly; they organize child codes that share clinical context. Coders should select the billable child code that matches the documented presentation and then verify its current source-backed HCC mapping. Do not infer a child code or risk adjustment value from the header alone.
HCC Buddy maintains structured V28 and V24 mapping, source-labeled coefficient references, and MEAT documentation criteria for N27 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Includes
- oligonephronia