Figure 2.

Simple step model of eGFR by age and serum creatinine. When the eGFR is above 60 ml/min/1.73 m² body surface, protein restriction is not necessary, although the recommended dose is 0.8 g/kg b.wt. When the eGFR is lower than 60 ml/min, protein restriction should start, aiming at a daily intake of 0.5 g/kg b.wt. When the eGFR becomes less than 30 ml/min/, further protein restriction is necessary (0.4 g/kg). If the eGFR decreases under 10 ml/min/, the patient needs hemodialysis or kidney transplantation. The eGFR is easily estimated from a chart computing age and serum creatinine. For example, if the patient is 40-years old and the serum creatinine is 2.0 g/dL, the color of the crossing area is orange, so the corresponding protein restriction should be 0.4 g/b.wt.