STIMULATING ACTION OF CALCIUM ON THE HYPOTHALAMIC-PITUITARY-ADRENAL AXIS

ABSTRACT The effect of calcium on the hypothalamic-pituitary-adrenal system was studied in 10 subjects – 9 with normal adrenal function and in 1 adrenalectomized patient – by giving an intravenous infusion of calcium during 4 hours. In all the subjects with intact hypothalamic-pituitary-adrenal axis the level of plasma 11-OHCS either was increased or the fall was diminished as compared to the fall in plasma 11-OHCS during an intravenous infusion of glucose. However, no correlation was found between the plasma calcium and the 11-OHCS. Furthermore the excretion of 17-KGS in the urine was unaltered during the calcium infusion experiments. In the adrenalectomized patient no difference in the plasma 11-OHCS was found during calcium or glucose infusion. It is concluded that calcium stimulates the hypothalamic-pituitary-adrenal system, resulting in an increased cortisol secretion. The level at which this stimulation occurs remains unknown.