Hormone, calcium and blood pressure relationships in primary hyperparathyroidism

Abstract

The cause of hypertension in primary hyperparathyroidism and its response to corrective surgery remains a matter of controversy. We therefore studied blood pressure, vasoactive hormones and plasma calcium responses to parathyroidectomy in six hypertensive and two normotensive patients with primary hyperparathyroidism. Twenty-four-hour intra-arterial pressure recordings, together with hourly blood sampling for plasma renin activity (PRA), aldosterone, cortisol, catecholamines and calcium levels, were undertaken in each patient before surgery and were repeated under identical conditions 3–6 months after parathyroidectomy. Mean plasma calcium was 3.03 ± 0.1 before, and 2.35 ± 0.02 mmol/l after, parathyroidectomy. Changes in arterial pressure were small and variable in individual patients. Group mean arterial pressures before and after surgery were identical. Plasma cortisol and PRA were significantly higher in the hypercalcaemic state (P<0.01 and P<0.05, respectively) but there was no significant difference in plasma aldosterone or catecholamine levels. No correlations between changes in plasma calcium or parathyroid hormone levels and concomitant changes in plasma concentration of other hormones were observed. Our findings show that correction of primary hyperparathyroidism has no systematic effect on arterial pressure in a heterogeneous group, including some patients with probable background essential hypertension, when evaluated 3-6 months after surgery. Compared with values after corrective surgery, mean levels of PRA and cortisol – but not aldosterone or catecholamines—are elevated in patients with primary hyperparathyroidism. These findings are consistent with an inhibitory effect of raised ionic calcium concentration on the response of the adrenal glomerulosa to angiotensin and adrenocorticotrophic hormone.