Stage 1 is normal and stage 5 is generally dialysis
The stages are defined by the estimated glomerular filtration rate (egfr) with cut points as follows:
stage 1 >90ml/min
stage 2 > 60 ml/min
stage 3 > 30 ml/min
stage 4 > 15 ml/min
stage 5 < 15 ml/min
the egfr is obtained by either the cockroft gault or the mdrd method.