Clinical meaning
The KDIGO classification stages CKD using a two-dimensional matrix combining GFR categories and albuminuria categories. GFR stages: G1 (≥90, normal), G2 (60-89, mildly decreased), G3a (45-59, mild-moderate), G3b (30-44, moderate-severe), G4 (15-29, severe), G5 (<15, kidney failure). Albuminuria categories: A1 (<30 mg/g, normal), A2 (30-300, moderately increased/microalbuminuria), A3 (>300, severely increased/macroalbuminuria). G1-G2 require evidence of kidney damage (albuminuria, structural abnormality) to qualify as CKD. The heat map assigns risk colors guiding monitoring frequency: green (annual), yellow (annual), orange (every 6 months), red (every 3 months). Management intensity increases with both declining GFR and increasing albuminuria.
Diagnosis & workup
Diagnostics & workup: - eGFR via CKD-EPI equation: two values ≥3 months apart confirming persistence - UACR: spot urine sample; confirm abnormal result on repeat testing (exclude transient causes: exercise, fever, UTI, menstruation) - Combine GFR category (G1-G5) and albuminuria category (A1-A3) for complete staging - KDIGO heat map determines: monitoring frequency, intensity of RAAS blockade, referral timing, complication screening frequency - Rate of eGFR decline: calculate slope from serial values; >5 mL/min/year = rapid progression - Stage-appropriate complication screening: G3a+: electrolytes, calcium, phosphorus, PTH annually; G4+: add Hgb, iron studies every 6 months