Effect of Recombinant Human Growth Hormone on Urinary ¹⁵N-Nitrogen Balance in Girls with Turner Syndrome as Compared to Children with Growth Hormone Deficiency

Abstract

¹⁵N-nitrogen balances before and on human growth hormone (hGH) were studied in 13 girls with Turner syndrome (TS) aged 4.4–16 (median 13.2) years (45, X0 or equivalent, no X0/XX mosaicism, no estrogen replacement). The results were compared with those reported from 9 patients with growth hormone deficiency (GHD). The TS patients received subcutaneous hGH doses of 2 × 3 (group A, n = 6), 3 × 2 (group B, n = 3), or 2 × 6 (group C, n = 4) IU/m² on consecutive days. The mean ¹⁵N dose given to the patients of groups A and C was higher (13.6 mg/kg) than that given to those of group B (2.7 mg/kg). The lower hGH doses in the first two groups induced small positive mean ¹⁵N balance changes (+0.6 ± 0.6 mg/kg ¹⁵N, group A; +0.03 mg/kg, group B). The higher hGH dose in group C caused a more marked mean balance change (+3.0 mg/kg ¹⁵N) comparable to that in GHD patients (+3.2 mg/kg). Individual variation of response, however, was larger in patients with TS than in those with GHD. With low and high hGH doses, there were responders and nonresponders. It is concluded from this pilot study in a small number of cases that ¹⁵N balance studies might be potentially useful to choose the appropriate hGH dose for long-term treatment in TS patients.