Renin-angiotensin-aldosterone system in primary hyperparathyroidism beforeand after surgery

Twenty consecutive unselected patients with proven primary hyperparathyroid ism (PH), 26 essential hypertensive (EH) patients, and 13 normotensives wer e studied. Blood pressure (BP) and, under constant salt intake, plasma reni n activity (PRA), parathyroid hormone (PTH), urinary and plasma sodium, pot assium, aldosterone (ALD), creatinine, total calcium, and phosphate were me asured. Patients with PH were also studied 1 and 6 months after successful surgery. In patients with PH, systolic and diastolic BP was significantly l ower (P < .001) than in EH patients and higher (P < .005) than in controls. Eight patients with PH (40%) had BP levels greater than 140/90 mm Hg. PTH and plasma and urinary calcium in patients with PH were significantly (P < .01) higher than in controls, while PR, ALD, phosphate, potassium, and sodi um were superimposable in the three groups. PTH in patients with PH was wea kly correlated with PRA (positively) and with plasma potassium (negatively) and was not associated with ALD, calcium, sodium, and BP levels. Surgery w as followed by a significant reduction (P < .01) in PTH, calcium, and urina ry phosphate and an increase (P < .02) in plasma phosphate, potassium, and sodium, whereas PRA, ALD, urinary potassium and sodium, and BP showed no ch ange. In hypertensive patients with PH, PTH, PRA, and plasma and urinary AL D, calcium, and sodium did not differ from the values in normotensive PH pa tients, and variations in these humoral parameters after surgery were compa rable in the two groups. In conclusion, our results show that hypertension is frequently associated with PH. However, the present data raise doubts ab out the assumption of a renin-mediated causal relationship between hyperpar athyroidism and high BP. Indeed, as a unique finding in favor of the hypoth esis of a stimulating role of PTH in renin secretion, we observed only a we ak relation between PTH and PRA. Thus, unknown and/or unassessed factors re lated to parathyroid disease cannot be ruled out to explain the hypertensio n observed in some patients with PH. Copyright (C) 1999 by W.B. Saunders Co mpany.