Calcium regulating hormones in essential hypertension. Importance of gender. Alterations of calcium metabolism have been described in human essential hypertension and experimental hypertension. We investigated the interrelationship of parathyroid hormone (PTH) and 1,25(OH)2-vitamin D (1,25(OH)2D) in patients with untreated essential hypertension as compared to normotensive controls. The hypertensive subjects (n = 75; 43 men, 32 women) had a mean blood pressure of 138 +/- 8/95 +/- 5 mm Hg as compared with 120 +/- 11/80 +/- 8 in the normotensive group (n = 40; 22 men, 18 women). Serum PTH was measured with an intact molecule immunochemiluminometric assay and 1,25(OH)2D was measured with radioimmunoassay after HPLC separation. Hypertensive men had PTH levels that were 36% higher than normotensive men (5.3 +/- 2.9 v 3.9 +/- 0.8 pmol/L, P = .005). When blood pressure was analyzed as a continuous variable, there was a direct correlation between it and serum PTH in men (r = .31, P = .004). In women, by contrast, there was no difference in serum PTH between hypertensive and normotensive subjects and no relationship between blood pressure and the serum PTH concentration. Blood pressure was inversely correlated with serum phosphorus levels in both sexes (r = -0.20, P = .04). In men, the elevated serum PTH levels and depressed serum phosphorus levels would have predicted that serum 1,25(OH)2D would be higher in the hypertensive subjects. However, that was not observed, as serum 1,25(OH)2D was slightly lower in hypertensive (38.3 +/- 15.2 pg/mL) than normotensive men (42.7 +/- 11.3, P = .21). 