What is the cutoff for stage 2 kidney disease in terms of glomerular filtration rate (GFR)?

Stage 2 Chronic Kidney Disease GFR Cutoff

Stage 2 chronic kidney disease is defined by a glomerular filtration rate (GFR) of 60-89 mL/min/1.73 m² with evidence of kidney damage. 1, 2

CKD Staging Based on GFR

• Stage 1: GFR ≥90 mL/min/1.73 m² with evidence of kidney damage 2
• Stage 2: GFR 60-89 mL/min/1.73 m² with evidence of kidney damage 1, 2
• Stage 3: GFR 30-59 mL/min/1.73 m² (subdivided into 3a: 45-59 and 3b: 30-44) 1, 2
• Stage 4: GFR 15-29 mL/min/1.73 m² 1, 2
• Stage 5: GFR <15 mL/min/1.73 m² or dialysis 1, 2

Important Diagnostic Considerations

• For both Stage 1 and Stage 2 CKD, evidence of kidney damage must be present in addition to the GFR criteria 2

• Evidence of kidney damage includes: 2, 3

  • Albuminuria (urinary albumin-to-creatinine ratio ≥30 mg/g) 1
  • Proteinuria 2
  • Hematuria 2
  • Pathological abnormalities on kidney biopsy 2
  • Abnormalities in imaging tests 2

• The kidney damage must be present for at least 3 months to differentiate CKD from acute kidney injury 2, 3

Clinical Implications of Stage 2 CKD

• Even with mild GFR reduction (60-89 mL/min/1.73 m²), patients with evidence of kidney damage have increased cardiovascular risk 4
• Patients with Stage 2 CKD should be evaluated and treated for dyslipidemia and other cardiovascular risk factors 1
• Stage 2 CKD patients have a higher prevalence of multiple cardiovascular risk factors compared to those with normal kidney function (44.9% vs 34.7% have 2 or more risk factors) 4

Measurement Considerations

• GFR is typically estimated using equations based on serum creatinine or cystatin C 5
• The most commonly used equations are the MDRD (Modification of Diet in Renal Disease) and CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) formulas 6
• CKD-EPI equation is generally preferred as it can overcome constraints of other formulas, especially in patients with diabetes 6

Common Pitfalls and Caveats

• Relying solely on GFR without evidence of kidney damage can lead to overdiagnosis, especially in elderly patients 1, 7
• GFR physiologically decreases with age, and in adults older than 70 years, values below 60 mL/min/1.73 m² may be considered normal 7
• Laboratory reports often don't provide specific numeric values for eGFR >60 mL/min/1.73 m², making it difficult to distinguish between normal kidney function and Stage 2 CKD without evidence of kidney damage 1
• Restricting routine testing to patients at increased risk of CKD reduces false-positive results 1

Management Implications

• Early detection of Stage 2 CKD allows for interventions that may slow progression to more advanced stages 2
• Management should focus on treating underlying causes and modifiable risk factors 1
• For patients with diabetes and Stage 2 CKD, glycemic and blood pressure control are essential 1