Glomerular filtration rate fails to increase following protein ingestion in hypothalamo-hypophyseal-deficient adults. Preliminary observations.

Abstract

Oral protein loads are known to induce an increase in glomerular filtration rate (GFR) in man and animals. The mechanism underlying this phenomenon is currently unknown. In order to study the possible role of growth hormone (GH) or other hypothalamo-hypophyseal (HH) factors in the response of GFR to a protein meal, we studied 4 chronically GH- or HH-deficient adults and age-matched controls, free of renal disease, before and after ingestion of a large protein meal (red cooked meat). GFR, measured by inulin clearance and corrected for body surface area, was 18.5% lower during basal conditions (89.1 +/- 6.0 ml/min) in the GH- or HH-deficient population when compared to controls (109.7 +/- 9.1 ml/min), but this difference did not achieve statistical significance for this small patient population (p greater than 0.1, less than 0.2). For a 3-hour postprandial period, mean GFR increased by 25.3% in the control population (136.8 +/- 10.7 ml/min; p less than 0.01), while mean GFR failed to increase in the GH- or HH-deficient patients (86.8 +/- 10.9 ml/min; p greater than 0.10). Male control subjects, not pretreated with diethylstilbestrol, had no change in GH levels (p greater than 0.2). However, 1 female control was found to increase GH levels 10 times preprandial levels. These studies suggest that HH factors other than GH are mediators of the augmentation of GFR following a large protein load in human adults.