GRF-INDUCED AND NOCTURNAL GH SECRETION IN THALASSEMIC CHILDREN

To test the hypothesis of an hypothalaaic origin of the growth retardation observed in thalasseiic children at the time of puberty, 18 males and 6 females, aged 9 to 20 years, have been studied under high-regimen blood transfusion and desferrioxamine therapy for the GH response to GRF (2ug/kg, 1-44 NH2, Sanofi), conventional tests and sleep. Pubertal stages according to Tanner Mere as follows: 6 M and 4 F at stage 1, 8 H at stage 2 and 4 N and 2 F at stage 3 or more. 13 M and 5 F showed evidences of hypogonadotropic hypogonadism. The conventional test responses were norial in 17 and low in 7 patients. A blunted response to GRF was seen in 2 patients which previously show normal pharmacological response. The GH nocturnal peak was above 20 uI/ml in 14 patients. 8 have a decreased nocturnal secretion in contrast to normal GRF response. The mean values of the nocturnal-and GRF-induced peaks were below normal for the age. There was no correlation between the conventional GH response and GRF or sleep response. The nocturnal response was correlated with the GRF-induced peak but not with either bone-age retardation, growth velocity or ferritin blood level. In conclusion thalassemic children show evidences of GH dysfunction suggesting a privacy hypothalamic dysfunction and/or an secondary effect of hypogonadism on the GH secretion likely related to hemosiderosis.