Decreased bone mineral density in prepubertal children with sickle cell disease: correlation with growth parameters, degree of siderosis and secretion of growth factors.

Patients with sickle cell disease (SCD) frequently have bone disorders of multifactorial aetiology. We attempted to analyse the relationships between bone mineral density (BMD) on the one hand and auxologic parameters, degree of siderosis, function of the growth hormone (GH)/insulin-like growth factor-I (IGF-I)/IGF-binding protein 3 (IGFBP3) axis, and calcium-phosphate balance in 28 prepubertal children with SCD and 15 age-matched children with constitutional short stature (CSS). Children with SCD had significantly decreased BMD (77.9 +/- 11.9 per cent of normal BMD for age and sex) and circulating concentrations of IGF-I (91 +/- 31 ng/ml) and IGFBP3 (1.7 +/- 0.44 mg/l) compared with the control group (BMD = 93.5 +/- 8.2 per cent of normal BMD for age and sex, IGF-I = 221 +/- 48 ng/ml, and IGFBP3 = 2.3 +/- 0.34 mg/ml). GH response to provocation was defective (peak below 10 micrograms/l) in 40 per cent of children with SCD. Those with SCD with defective GH secretion had significantly lower circulating IGF-I concentration and BMD than those with normal GH secretion. Serum calcium, phosphate and alkaline phosphatase concentrations were normal in all children with SCD. BMD was correlated significantly with height, weight, and body mass index as well as with the circulating concentrations of IGF-I and IGFBP3. It is suggested that increasing the circulating IGF-I concentration, either through increasing the caloric intake of subjects and/or via GH/IGF-I therapy, may improve growth and bone mineralization in these patients.