Reduced insulin growth factor I concentrations in iron-overloaded beta thalassaemic patients with normal growth hormone secretion and liver function.

We selected 92 subjects (46 females and 46 males), aged 10-15 years, from the Haematology and Endocrine Clinic of Shiraz University, Iran. Forty-six were beta thalassaemia patients (beta-Th) with short stature, 23 had idiopathic short stature (ISS) and 23 were healthy children with a standing height between the 10th and 95th percentile. Growth hormone (GH) secretion was normal in 23 beta-Th patients and reduced in the remaining 23 patients. A low insulin growth factor I (IGF-I) was found in 73.9% of beta-Th patients with GH deficiency, 56.5% of beta-Th patients with normal GH secretion to stimulation test and 8.7% of children with ISS. The reduced IGF-I concentration in beta-Th patients with normal GH secretion may be explained by partial insensitivity to GH (GHIS), neurosecretory dysfunction, low bioactive GH or increased proportion of circulating, non-22-kDa GH isoform. The possibility of GHIS in beta-Th patients with short stature indicates that higher doses of rechGH may be required to obtain an improvement in growth velocity in beta-Th patients.