Decreased trabecular bone mineral density in children with idiopathic short stature: Normalization of bone density and increased bone turnover after 1 year of growth hormone treatment

Abstract

Patients with growth hormone (GH) deficiency have impaired bone mineral metabolism; treatment with GH leads to an improvement in their bone mineral density (BMD). The effect of GH on the BMD of children with idiopathic short stature is unknown. We studied 14 short, slowly growing, otherwise healthy, prepubertal children without GH deficciency (7 girls and 7 boys) with a chronological age of 10.9 ± 1.4 years, bone age of 8.8 ± 1.5 years, and height of 127.8 ± 8.5 cm (height SD score of –2.2 ± 0.5). Growth velocity increased from 3.9 ± 1.1 cm/y to 8.0 ± 1.9 cm/y, and height SD score improved from –2.2 ± 0.5 to -1.8 ± 0.5 after 12 months of GH treatment ( P < .007 and P < .001, respectively). Baseline lumbar spine BMD was decreased when compared with that of a control group of children matched for bone age and height (0.645 ± 0.09 g/cm 2 vs 0.730 ± 0.08 g/cm 2; P < .003). Lumbar spine BMD increased in subjects with ISS after 1 year of GH treatment from 0.645 ± 0.09 g/cm 2 to 0.808 ± 0.04 g/cm 2 ( P < .05), reaching levels similar to those of control subjects, followed up without therapy (0.808 ± 0.04 g/cm 2 vs 0.760 ± 0.08 g/cm 2); lumbar spine BMD increased 25.3% in the subjects with ISS and 4.1% in the control subjects. Femoral neck BMD did not change during treatment. Serum concentrations of the carboxy-terminal propeptide of type 1 collagen increased from 231.6 ± 65.5 μg/L to 351.6 ± 87.2 μg/L, and levels of the carboxy-terminal cross-linked telopeptide of type 1 collagen increased from 9.9 ± 5.9 μg/L to 13.9 ± 2.4 μg/L. Children with ISS have decreased lumbar spine BMD, which increases with GH therapy, reaching levels similar to those of control subjects. Bone turnover increased as indicated by a rise in bone formation and bone resorption markers. (J Pediatr 1999;135:177-81)