Circadian pattern of circulating plasma ACTH, cortisol, and aldosterone in patients with beta-thalassemia.

Plasma levels of ACTH, cortisol, and aldosterone were measured for an entire day every 2 h, starting from midnight, in 4 healthy subjects, and in 4 patients with beta-thalassemia, without evidence for any endocrine disease. The subjects, after synchronized standard life conditions for 10 days, were held in constant supine position during the study. The data were analysed by the "cosinor" method. The results show significant circadian rhythms for the three biological variables in healthy subjects. In the thalassemic patients a significant circadian rhythm was detected only for cortisol and aldosterone. No rhythm was demonstrated for ACTH in the patient group. While no differences were found in mesors and acrophases for the three hormones between the two groups, a significant difference was observed regarding amplitudes. These data suggest that in beta-thalassemia, the secretion rhythmicity of ACTH is modified, whereas the adrenal cortex maintains its own physiologic rhythmicity in hormone secretion.