What are the criteria to diagnose chronic kidney disease?

Diagnostic Criteria for Chronic Kidney Disease

Chronic kidney disease is diagnosed when either kidney damage OR a GFR <60 mL/min/1.73 m² persists for 3 months or longer. 1

Two Pathways to Diagnosis

You can establish CKD through either of these criteria:

Pathway 1: Evidence of Kidney Damage (at any GFR level)

• Albuminuria: Albumin-to-creatinine ratio (ACR) ≥30 mg/g in untimed urine samples 1
  • Sex-specific cutpoints: >17 mg/g in men, >25 mg/g in women 1
  • Must be persistent (confirmed on 2 of 3 spot urine specimens) 2
• Abnormal urine sediment (e.g., hematuria, cellular casts) 1
• Abnormal blood/urine chemistry indicating tubular disorders 1
• Abnormal kidney imaging (structural abnormalities, masses, obstruction) 1
• Kidney biopsy showing pathologic changes 1

Pathway 2: Reduced GFR Alone

• GFR <60 mL/min/1.73 m² for ≥3 months is diagnostic by itself, even without other markers of damage 1
• This threshold represents loss of half or more of normal adult kidney function 1
• Normal GFR in young adults is approximately 120-130 mL/min/1.73 m² 1

Critical Timing Requirement

The 3-month duration is mandatory to distinguish CKD from acute kidney injury or acute kidney diseases 1. Any abnormality—whether reduced GFR, albuminuria, or structural damage—must persist beyond 3 months to meet diagnostic criteria 1.

GFR Estimation Method

• Use the CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) equation for estimating GFR from serum creatinine 1
• The CKD-EPI equation has less bias than the older MDRD equation, especially at GFR ≥60 mL/min/1.73 m² 1
• Creatinine assays must be calibrated to isotope-dilution mass spectrometry reference method 1

Confirmatory Testing for Borderline Cases

For patients with eGFR 45-59 mL/min/1.73 m² (Stage G3a) without albuminuria or other damage markers, measure cystatin C to confirm the diagnosis 1. This is particularly important because:

• This group represents 41% of persons in the U.S. estimated to have CKD based on creatinine alone 1
• Two-thirds will have CKD confirmed by cystatin C-based eGFR <60 mL/min/1.73 m² 1
• Those confirmed have markedly elevated risks for death, cardiovascular disease, and end-stage renal disease 1

Common Diagnostic Pitfalls

Do not diagnose CKD in patients with eGFR ≥60 mL/min/1.73 m² unless they have documented markers of kidney damage 1, 3. Simply having an eGFR ≥60 mL/min/1.73 m² without albuminuria, abnormal imaging, or other damage markers does not constitute CKD, regardless of other risk factors 3.

Age-related GFR decline does not exclude the diagnosis—decreased GFR in elderly patients is an independent predictor of adverse outcomes including death and cardiovascular disease, requiring the same diagnostic criteria regardless of age 1.

Do not use creatinine clearance or estimated creatinine clearance as these overestimate GFR and lead to misclassification 3.

Laboratory Reporting Standards

• Laboratories should report ACR and protein-to-creatinine ratio (PCR) in untimed urine samples, not just concentrations alone 1
• Discontinue use of the term "microalbuminuria" in laboratory reporting 1
• Report numerical eGFR values across the full range, not just "<60" 1