Growth hormone therapy in hypophosphatemic rickets
D. M. Wilson, P. D. Lee, A. H. Morris, E. O. Reiter, J. M. Gertner, R. Marcus, V. E. Quarmby and R. G. Rosenfeld
Department of Pediatrics, Stanford University, Calif.
The effects of growth hormone therapy on the biochemical measures of bone
metabolism were studied in 11 children aged 3.5 to 17 years who had
familial hypophosphatemic rickets; five were male. Subjects were maintained
on a regimen of stable doses of conventional therapy (calcitriol and
phosphate). Subjects were studied at baseline receiving conventional
therapy and during three sequential treatment periods: no therapy (4
weeks), growth hormone only (0.05 mg/kg per day for 4 weeks), and
conventional therapy plus growth hormone (2 weeks). The nine youngest
subjects were continued on a regimen of triple therapy for an additional 24
weeks. Serum phosphate averaged 0.93 +/- 0.13 mmol/L (mean +/- SD) at entry
and decreased when the subjects were not receiving any therapy. During the
4 weeks of growth hormone only treatment, phosphate rose in all 11 subjects
(0.70 +/- 0.08 mmol/L to 0.83 +/- 0.08 mmol/L). With triple therapy,
phosphate remained higher than with no therapy. Calcitriol, osteocalcin,
and parathyroid hormone increased as the subjects received growth hormone
alone. Insulinlike growth factor I z scores rose significantly in response
to growth hormone therapy alone. All nine subjects receiving 6 months of
triple therapy increased their growth rate z scores. Exogenous growth
hormone therapy may be useful in familial hypophosphatemic rickets.
