Age changes in glomerular filtration rate, effective renal plasma flow, and tubular excretory capacity in adult males.

It has previously been shown that inulin clearance, diodrast clearance, and diodrast Tm are significantly lower in males between the ages of 60 and 80 years than in males 20-40 years of age (1, 2). The clearance and Tm values commonly used as norms are based on averages calculated from observations made on subjects between the ages of 17 and 68 years (3-5). The present study was undertaken to evaluate the rate of the age changes in renal functions previously reported.