Kidney function and size in normal subjects before and during growth hormone administration for one week.

Kidney function and size were studied in seven normal male subjects before and after administration of highly purified human growth hormone for 1 week. Glomerular filtration rate, renal plasma flow (steady-state infusion technique with urinary collections using 125I-iothalamate and 131I-hippuran) kidney size (ultrasonic scanning) and urinary excretion rates of albumin and beta 2-microglobulin (radioimmunoassays) were measured. Highly purified growth hormone was injected subcutaneously, 2 IU in the morning and 4 IU in the evening. Glomerular filtration rate increased from (mean +/- SEM) 114 +/- 5 to 125 +/- 4 ml/min x 1.73 m2 (P less than 0.01) and renal plasma flow increased from 554 +/- 30 to 601 +/- 36 ml/min x 1.73 m2 (P less than 0.01). Kidney size and urinary excretion rates of albumin and beta 2-microglobulin did not change significantly. Our results show that raising plasma growth hormone into a range similar to that found in insulin-dependent diabetics enhances glomerular filtration rate and renal plasma flow, while kidney size remains unchanged. Increased renal plasma flow is the major determinant of growth hormone induced elevation in glomerular filtration rate. Growth hormone may thus contribute to the enhancement of glomerular filtration rate and renal plasma flow typically found in insulin-dependent diabetics.