Relationship between serum parathyroid hormone levels in the elderly and 24 h ambulatory blood pressures

An association between serum parathyroid hormone (PTH) levels in normotensive elderly subjects and blood pressure values had been reported.

To examine the relationship between PTH levels and other biochemical markers of calcium metabolism in elderly subjects and 24 h ambulatory blood pressures.

We performed 24 h ambulatory blood pressure recordings for 123 independent elderly subjects aged 63-88 years using a SpaceLabs 90207 recorder. Mean night-time blood pressures were calculated from the average of readings during sleep; mean daytime blood pressures were calculated from the remaining recordings. Demographic data and details concerning the alcohol consumption and medication usage of the subjects were recorded. Serum PTH, 25-hydroxy-vitamin D, albumin, renin, aldosterone, noradrenaline, creatinine and calcium levels were measured.

Fifty-five patients were being administered antihypertensive therapy. Serum PTH levels correlated to the nocturnal systolic blood pressure (SBP; beta = 0.29, P = 0.002), nocturnal diastolic blood pressure (DBP), daytime SBP and mean 24 h SBP on univariate and multivariate analysis. Aldosterone levels were related to nocturnal SBP in univariate analysis (beta = 0.21, P = 0.02) but the relationship was weakened when PTH levels were included in the analysis (beta = 0.16, P = 0.09). Nocturnal, daytime and mean 24 h blood pressures were not significantly related to serum calcium, 25-hydroxy-vitamin D, age, body mass index and alcohol consumption. Sex was a significant predictor of the DBP, men having higher levels than did women (daytime DBP beta = 0.29, P = 0.001).

Serum PTH levels are related strongly to the blood pressure, particularly the nocturnal blood pressure in the elderly. It is not known whether PTH levels are a consequence or a cause of the elevation in blood pressure.