Effect of alendronate on bone mineral density in adult patients with Laron syndrome (primary growth hormone insensitivity)

Severe short stature resulting from a deficiency in insulin-like growth factor-I (IGF-I) is a prominent feature of Laron syndrome (LS). Whether patients with LS are osteopenic or not, and whether they need treatment with bisphosphonates, remains uncertain. The aim of this study was to investigate the action of alendronate on the IGF-I-deficient bones of adult patients with LS and osteoporosis, as determined by dual X-ray absorptiometry . Seven patients (5 women and 2 men) of mean age 40.8 ± 7.6 years and mean bone mass density (BMD) 0.843 ± 0.06 g/cm2 (T score −2.9 ± 0.5) at the lumbar spine and 0.734 ± 0.11 g/cm2 (T score −2.2 ± 0.9) at the femoral neck were treated with alendronate 70 mg once/weekly over a 12-month period. Treatment led to an increase of 5.3% in BMD (p = 0.038) at the femoral neck. There was a similar trend at the lumbar spine, but the difference was not statistically significant (2.3%, p = 0.34). Mean total alkaline phosphatase decreased by 14% from normal range at baseline (p = 0.007). Urinary deoxypyridinoline levels, which were elevated at baseline (10 ± 2.3 nM/mMcre), showed a nonsignificant change during treatment. Our study suggests that treatment with alendronate may have positive effects in patients with LS and low BMD on dual X-ray absorptiometry.