AGE CHANGES IN GLOMERULAR FILTRATION RATE, EFFECTIVE RENAL PLASMA FLOW, AND TUBULAR EXCRETORY CAPACITY IN ADULT MALES

Abstract
Renal clearance and Tm values commonly used as norms are based on measurements in individuals between ages of 17 and 68 yrs. A study of the age changes in inulin clearance (ClI), diodrast clearance (CId), and diodrast Tm (TmD) in 70 malc subjects between 24 and 89 yrs. of age with no evidence of frank cardiovascular renal disease. Uncomplicated arteriosclerosis was not ruled out. In 7 decades, ClI fell gradually from 122.8 to 65.3, ClD from 613.5 to 288.8 cc./min./1.73 sq. m. Filtration fraction (x 100) showed a small but significant increase. C1I/TmD did not change, but CID/TmD, the effective renal plasma flow per unit of excretory capacity, decreased significantly with age.
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