IMPAIRED RESPONSE OF FREE ALPHA-SUBUNITS AFTER LUTEINIZING-HORMONE-RELEASING HORMONE AND THYROTROPIN-RELEASING-HORMONE STIMULATIONS IN BETA-THALASSEMIA MAJOR

In order to clarify whether the damage in gonadotropin secretion due t o iron overload in patients with beta-thalassemia's of pituitary or hy pothalamic origin, 14 euthyroid patients (8 females and 6 males, age 1 5-24 years) affected by beta-thalassemia major with hypogonadotropic h ypogonadism were studied. Luteinizing-hormone (LH), follicle-stimulati ng hormone (FSH) and free alpha-subunit (FAS) were measured during LH- releasing hormone (LH-RH) stimulation test, and thyroid-stimulating ho rmone (TSH), prolactin (PRL) and FAS during thyrotropin-releasing horm one (TRH) stimulation test. During LH-RH stimulation, the mean basal L H, FSH and FAS levels were similar to those found in normal prepuberta l children, but the peak values were lower than those found in such ch ildren. Also during TRH stimulation, the mean peak values of FAS were lower than those of normal prepubertal children, but the TSH response was normal. The lack of response of gonadotropins and FAS to LH-RH can not exclude hypothalamic failure; however, the normal response of TSH to TRH, in spite of the poor response of FAS, indicates that the origi n of hypogonadotropic hypogonadism is the pituitary damage concerning not only the gonadotroph but also the thyrotroph cells.