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.