Abstract

Pituitary, adrenal, and pancreatic functions were investigated in 9 patients with thalassaemia major. 9 a.m. plasma ACTH values were 148-480 pg/ml (normal range 15-70 pg/ml). Cortisol and growth hormone response to insulin-induced hypoglycaemia was normal in all. 24-hour urinary excretions of 17-ketosteroids and 17-hydroxycorticosteroids were normal. There was normal cortisol response to intramuscular injection of ACTH. In a physiological adrenal stimulation test there was a significantly smaller response to each physiological dose of tetracosactrin. 4 patients had diabetic glucose tolerance tests--none are clinically diabetic. The mean plasma glucose utilization constant (Kgl=2-02) is significantly smaller than normal. Plasma insulin response both in the oral and the intravenous glucose tolerance test was significantly smaller than normal. The data were consistent with severe and widespread impairment of endocrine function and a plausible explanation would be iron deposition in endocrine organs. It is suggested that pituitary hyperfunction of ACTH secretion is due to target organ unresponsiveness which can be shown in its early stages only by a physiological test of the adrenal cortex. Skin pigmentation in thalassaemia seems to be due to the melanophore-stimulating effect of this raised plasma ACTH.