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

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

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

METHODS: 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.

RESULTS: 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).

CONCLUSIONS: 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.