HealthAssure
HealthAssureGood Life
ICD10BillableValid for clinical use

ICD-10 Code N18.1: Chronic kidney disease, stage 1

N18.1 is a billable ICD-10 diagnosis code used to classify Chronic kidney disease, stage 1 in medical records and claims. You may see this code in hospital records, discharge summaries, insurance claims, encounter documentation, referrals, or other healthcare billing and coding records. ICD-10 codes are diagnosis classification codes used in healthcare records, reporting, coding workflows, and billing support. This code sits within the broader ICD-10 area for Diseases of the genitourinary system (N00-N99).

What is this code?

ICD-10 codes are diagnosis classification codes used in healthcare records, reporting, coding workflows, and billing support. This code sits within the broader ICD-10 area for Diseases of the genitourinary system (N00-N99).

📋Clinical overview

This ICD-10 code is commonly used when documentation describes chronic kidney disease or long-term loss of kidney function. The most accurate code depends on the documented CKD stage, whether end-stage kidney disease is present, and how clearly the record links kidney status to the active problem list.

When is it used?

  • May be used when a clinician documents chronic kidney disease, stage 1 in a patient's medical record.
  • May appear in hospital records, claims, referrals, and clinical documentation.
  • This code can be used as a clinically usable diagnosis entry in standardized coding workflows.

What it does not mean

  • A code alone does not explain severity, treatment plan, or outcome.
  • A medical code should not be treated as a substitute for a doctor's diagnosis or advice.

🩺Clinical context

When commonly used
  • Primary care, nephrology, inpatient, and chronic-disease documentation where reduced kidney function is part of ongoing management.
  • Risk-adjustment, utilization-review, and care-continuity workflows where CKD stage affects medication review, monitoring, and longitudinal care planning.
Common workup
  • Common related testing on this page includes Serum creatinine, Estimated glomerular filtration rate (eGFR), Urine albumin creatinine ratio.
  • Related procedures or service context already linked on this page include Hemodialysis, Peritoneal dialysis, Dialysis access procedure.
Common management context
  • CKD follow-up often includes kidney-function laboratory review, urine testing, blood-pressure management, medication reconciliation, and monitoring for disease progression.
  • Documentation usually becomes more specific when the chart identifies CKD stage, dialysis status, transplant history, proteinuria, anemia, or mineral and bone complications.
  • Specialist context already linked on this page includes Nephrologist, General Physician.

🔍Key distinctions

Important notes
  • ICD-10 CKD coding is stage-sensitive, so documentation that clearly states stage 1 through stage 5 or end-stage renal disease usually determines the final code choice.
  • CKD may coexist with diabetes, hypertension, anemia, or other chronic conditions, but separate linked diagnoses may still require their own more specific codes.
Related codes to consider
N18.2Chronic kidney disease, stage 2 (mild)
Related chronic-kidney-disease ICD-10 code; documentation often becomes more specific when the chart identifies CKD stage, end-stage disease, or associated kidney-status detail.
N18.3Chronic kidney disease, stage 3 (moderate)
Related chronic-kidney-disease ICD-10 code; documentation often becomes more specific when the chart identifies CKD stage, end-stage disease, or associated kidney-status detail.
N18.4Chronic kidney disease, stage 4 (severe)
Related chronic-kidney-disease ICD-10 code; documentation often becomes more specific when the chart identifies CKD stage, end-stage disease, or associated kidney-status detail.
N18.5Chronic kidney disease, stage 5
Related chronic-kidney-disease ICD-10 code; documentation often becomes more specific when the chart identifies CKD stage, end-stage disease, or associated kidney-status detail.

Code hierarchy

chapter
14Diseases of the genitourinary system (N00-N99)
block
N17-N19Acute kidney failure and chronic kidney disease
category
N18Chronic kidney disease (CKD)
currentN18

Where you may see this code

You may see this code in hospital records, discharge summaries, insurance claims, encounter documentation, referrals, or other healthcare billing and coding records.

Related specialists

NephrologistGeneral Physician

Related tests

Serum creatinine
Commonly reviewed in chronic kidney disease assessment.
Estimated glomerular filtration rate (eGFR)
Often used to assess kidney function stage and trend.
Urine albumin creatinine ratio
May help review protein leakage and kidney involvement.

Related procedures

Hemodialysis
May appear in advanced chronic kidney disease care pathways.
Peritoneal dialysis
May appear in advanced chronic kidney disease care pathways.
Dialysis access procedure
May be part of treatment planning when renal replacement therapy is needed.

Coding guidelines

Compatibility

Legacy and official ICD code match exactly.
Legacy codes
N18.1

Common synonyms

Chronic kidney disease, stage 1

Frequently asked questions

Code details

CodeN18.1
SystemICD10
Display nameChronic kidney disease, stage 1
ChapterDiseases of the genitourinary system (N00-N99)
BlockAcute kidney failure and chronic kidney disease

Flags

BillableYes
Valid clinical useYes

Source

SourceICD-10
Version2026-annual
Releaseannual
Year2026

Index terms

Matched terms
Disease, diseased

About this content

This page is prepared by HealthAssure's clinical team using official coding standards from ICD-10. AI tools assist with drafting explanations, which are then reviewed and verified by healthcare professionals for accuracy. This content is for informational purposes and does not replace professional medical advice. Meet our team.