Stimulation of nitrogen and whole-body protein metabolism in growth hormone-deficient children by recombinant human growth hormone: relationship to growth.

Abstract

The effect of a mammalian-cell-derived recombinant human growth hormone (rhGH) on nitrogen and whole-body protein metabolism was assessed in 12 children with complete growth hormone (GH) deficiency. All the patients received single oral doses of 15N-glycine (95 atom % 15N), 20 mg/kg body weight, prior to and following 7 days of treatment with rhGH, 1.7 IU/m2 body surface area (BSA) per day, administered subcutaneously. Prior to rhGH, mean urinary 15N-nitrogen excretion was 42.8 +/- 8% of the administered dose, which fell significantly to 22.8 +/- 7% during rhGH administration (p < 0.0001). Stimulation of protein metabolism by rhGH resulted in a protein net gain rate of 1.1 +/- 0.4 g/kg/day, which was significantly higher than the 0.6 +/- 0.5 g/kg/day rate seen prior to rhGH (p < 0.001). In patients subsequently placed on daily subcutaneous injections of rhGH 1.7 IU/m2 BSA, mean height velocity standard deviation score (HV SDS) for chronological age significantly increased from -3.8 +/- 2.6 to +8.5 +/- 3.1 and +3.3 +/- 2.2, during the 1st and 2nd years of treatment, respectively. However, there was no correlation between the long-term response to rhGH treatment and the short-term changes in nitrogen or protein metabolism in GH-deficient children.