Circadian growth hormone secretion in short multitransfused prepubertal children with thalassaemia major

Growth hormone (GH) secretion was determined by evaluating circadian GH profiles for 24 h and GH responses to clonidine stimulation test and insulin-stimulated hypoglycaemia (ITT), in nine prepubertal children with beta-thalassaemia major (TM) and 17 with non-GH deficient short stature (NGHDSS). The TM children were multitransfused and had early and intensive chelation therapy. All patients had normal hypoglycaemia to ITT, with peak GH levels of 15.71 +/- 5.86 ng/ml for children with NGHDSS and 13.91 +/- 7.20 ng/ml for children with TM. Peak GH levels during a clonidine test were 17.54 +/- 5.30 and 17.15 +/- 1.38 ng/ml, respectively. The GH peak parameters such as the number of peaks, the integrated GH concentration and the area under the curve (AUC) were similar in both groups of children and reflected the total 24-h secretion and the daily and nocturnal secretion separately. An abnormal 24-h GH profile compatible with the diagnosis of endogenous neurosecretory GH dysfunction was found in only two out of nine children with TM and in four out of seven children with NGHDSS. Our data suggest that growth hormone neurosecretory dysfunction is not a universal finding in children with thalassaemia major but might depend on the degree of iron deposit in the pituitary.