Urea synthesis, nitrogen balance, and glucose turnover in growth-hormone-deficient children before and after growth hormone administration.

We measured the effect of human growth hormone (hGH) on urea synthesis, nitrogen retention, and glucose turnover in ten euthyroid growth hormone (GH)-deficient children before and after seven daily injections of 0.1 U/kg hGH. The patients were fed a weight-maintaining diet with 9% of energy derived from protein. Following an overnight fast, urea synthesis and glucose turnover were determined using a primed constant infusion of [15N2] urea and a constant infusion of [6,6-2H2] glucose. Human growth hormone produced a decrease in urea nitrogen synthesis from 6.8 +/- 0.5 to 4.2 +/- 0.4 mg/kg.h; (P less than .01), while plasma urea nitrogen decreased from 13.1 +/- 0.8 to 7.4 +/- 0.8 mg/dL; (P less than .01). The decrease in urea synthesis was reflected in a corresponding decrease in urine urea nitrogen excretion (-2.8 mg/kg.h). There was a significant correlation between plasma urea nitrogen and urea synthesis rate both before (r = 0.85, P less than .01) and after (r = 0.79, P less than .01) hGH treatment. In response to hGH, there was a rise in both plasma glucose (81.4 +/- 2.2 v 89.8 +/- 2.3 mg/dL; P less than .05) and insulin (5.7 +/- 0.8 v 13.1 +/- 3.0 microU/mL; P less than .05), however, glucose turnover remained unchanged (4.7 +/- 0.3 v 4.6 +/- 0.6 mg/kg.min). After seven days of growth hormone treatment, the patients were placed on 0.1 U/kg of hGH three times a week for 6 months, and their growth rate was calculated.(ABSTRACT TRUNCATED AT 250 WORDS)