Changes in renal function with aging among Japanese.

Renal function was assessed in 329 inpatients who were presumably free of renal disease or water-electrolyte imbalance and the relationship between renal function and aging and sexual differences were investigated. Serum creatinine levels were slightly increased with aging, and were significantly higher in males than in females. Urinary creatinine excretion significantly decreased with aging; this decline was more pronounced in males. Urinary creatinine excretion was significantly higher in males. Creatinine clearance also decreased significantly with aging and this tendency was still observed after correction for body surface area. Sexual differences played no part in creatinine clearance. There was a significant increase in the serum beta 2-microglobulin level with aging. In addition, the Cer of the aged Japanese population was lower in comparison with western counterpart. The findings suggest the need for special consideration in conducting clinical tests or administering drugs to this segment of the population in Japan.