Hypogonadotropic hypogonadism in severe beta-thalassemia: effect of chelation and pulsatile gonadotropin-releasing hormone therapy

Abstract

We studied pituitary-gonadal function in 11 male and 5 female patients, aged 12-30 yr, with severe beta-thalassemia and chronic iron overload. All had normal basal serum cortisol, T4, and PRL concentrations and normal serum cortisol and GH responses to insulin-induced hypoglycemia and TSH responses to TRH. Of the 11 male patients (all over 17 yr of age), only 3 attained full pubertal development and 4 had subnormal serum LH and FSH responses to GnRH. As a group, their mean basal serum testosterone (T) level was low [11.7 +/- 4.9 (+/- SE) nmol/L; normal, 10-40 nmol/L], and 9 of the 11 male patients responded to hCG with a rise in serum T. Two of the 3 female patients over 17 yr of age were prepubertal with undetectable serum estradiol (E2) levels and absent serum LH and FSH responses to GnRH; the other female patient had regular menstrual cycles and normal serum E2 levels and LH and FSH responses to GnRH. Six of the prepubertal patients (4 males and 2 females, aged 17-30 yr) were studied serially for 3 yr after the start of chelation therapy. Despite a fall of median serum ferritin from 11,910 to 1,303 pmol/L, there was no progression of puberty, and their basal and GnRH-stimulated serum LH and FSH and serum T or E2 levels did not change. Three of these patients (1 male and 2 female) then received pulsatile sc GnRH therapy in addition to chelation therapy for 6 months with no improvement. We conclude that chronic iron overload in patients with severe thalassemia leads to variable degrees of hypogonadotropic hypogonadism, which do not respond to chelation therapy given late in the course of the disease. The hypogonadism in most patients was due to pituitary hyporesponsiveness to GnRH.