Diagnostic classification[1]

CKD is divided into 6 distinct categories based on glomerular filtration rate (GFR). The GFR category (G1-G5) has the same GFR thresholds as the CKD stages 1 to 5 recommended previously, as follows:[1]

  • G1: GFR >90 mL/minute/1.73 m², and evidence of kidney damage based on pathological diagnosis, abnormalities of radiographic imaging, or laboratory findings such as haematuria and/or proteinuria

  • G2 GFR 60 to 89: mL/minute/1.73 m²

  • G3a GFR 45 to 59: mL/minute/1.73 m²

  • G3b GFR 30 to 44: mL/minute/1.73 m²

  • G4 GFR 15 to 29: mL/minute/1.73 m²

  • G5 GFR <15: mL/minute/1.73 m².

The albumin category is also documented based on albumin excretion rate (AER) or albumin to creatinine ratio (ACR):

  • A1 AER <30 mg albumin/24 hours or ACR <3 mg/mmol (<30 mg/g): normal to mildly increased

  • A2 AER 30 to 300 mg albumin/24 hours or ACR of 3 to 30 mg/mmol (30 to 300 mg/g): moderately increased

  • A3 AER >300 mg albumin/24 hours or ACR >30 mg/mmol (>300 mg/g): severely increased.

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