Corticosteroid-induced hypothalamo-pituitary-adrenal axis suppression. Prospective study using two regimens of corticosteroid therapy.

Long-term oral corticosteroid therapy leads to suppression of the hypothalamo-pituitary-adrenal (HPA) axis (Paris, 1961; Treadwell, Savage, Sever, and Copeman, 1963; Jasani, Boyle, Greig, Dalakos, Browning, Thompson, andBuchanan, 1967). Much work has been done on the influence of the regimen of corticosteroid administration on this suppression. Harter, Reddy, and Thorn (1963) have presented evidence that administration of oral corticosteroid in a single dose given every other day leads to substantially less adrenal suppression than that which occurs with a regimen giving divided doses of corticosteroid over the same period. The doses used in this study were not physiological; that is to say patients received doses of prednisone or prednisolone-equivalent ranging from 20 to 40 mg. daily. Grant, Forsham, and DiRaimondo (1965) have shown that a daily morning dose of 8 mg. Triamcinolone administered to normal subjects over a period of 8 days does not lead to lasting adrenal suppression. Nichols, Nugent, and Tyler (1965) have demonstrated virtually complete suppression of the secretion of cortisol by the adrenal gland for a period of 24 hours following the administration of a physiological dose of corticosteroid (0 5 mg. dexamethasone) given at midnight. The same amount given at 8 a.m. or 4 p.m. caused only temporary suppression of cortisol secretion. In the present study we have compared the effect of two regimens of corticosteroid administration on