N18.1 ICD-10-CM Code: Chronic kidney disease, stage 1
HCC Buddy Code Card
Digital ICD-10 code-book layout with official code detail, always-visible risk models, Code Trumping, and Buddy coding guidance.
FY 2026 Apr update / Diseases of the genitourinary system (N00-N99) / Acute kidney failure and chronic kidney disease (N17-N19)
N18.1
Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidanceChronic kidney disease, stage 1
The earliest stage of chronic kidney disease where kidney function is normal or nearly normal, but there is evidence of kidney damage such as protein in the urine.
CMS-HCC V28
00
RAF 0
CMS-HCC V24
00
RAF 0
ACA/HHS
00
RAF 0
ESRD/PACE
00
RAF 0
RXHCC
00
RAF 0
Code Trumping
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Code Book Path
Inclusion Terms
OfficialICD-10-CM does not list inclusion terms for N18.1 in this effective period.
Excludes 2
OfficialICD-10-CM does not list Excludes 2 notes for N18.1 in this effective period.
Related Child Codes
Includes
OfficialICD-10-CM does not list Includes notes for N18.1 in this effective period.
Excludes 1
OfficialICD-10-CM does not list Excludes 1 notes for N18.1 in this effective period.
Code First
Official- any associated:
- diabetic chronic kidney disease (E08.22, E09.22, E10.22, E11.22, E13.22)
- hypertensive chronic kidney disease (I12.-, I13.-)
Use Additional
Official- code, if applicable, to identify:
- associated cachexia (E88.A)
- kidney transplant status (Z94.0)
Code Also
OfficialICD-10-CM does not list Code Also instructions for N18.1 in this effective period.
Buddy Documentation Tip
Last updated: FY2026 ICD-10-CM Apr update, Apr 1, 2026 through Sep 30, 2026. CMS-HCC V28 is 100% phased in for payment year 2026.
Is N18.1 an HCC code?
No. N18.1 is a billable ICD-10-CM code but does not map to any HCC category in V28, V24, ESRD, or RxHCC.
This code does not map to an HCC category in any model (V28, V24, ESRD, RxHCC).
What This Code Means
N18.1 is the ICD-10-CM diagnosis code for chronic kidney disease, stage 1. The earliest stage of chronic kidney disease where kidney function is normal or nearly normal, but there is evidence of kidney damage such as protein in the urine. N18.1 sits in the ICD-10-CM chapter for diseases of the genitourinary system (n00-n99), within the section covering acute kidney failure and chronic kidney disease (n17-n19).
N18.1 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.
Stage 1 CKD requires documentation of kidney damage (proteinuria, hematuria, imaging abnormalities) even though GFR is normal or near-normal (≥90).
HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for N18.1 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Stage 1 CKD requires documentation of kidney damage (proteinuria, hematuria, imaging abnormalities) even though GFR is normal or near-normal (≥90)
- •Always code the underlying cause of CKD (diabetes, hypertension, etc.) as an additional diagnosis when documented