The relation between serum parathyroid hormone (PTH) and blood pressure. The Tromsø study

The objective of the present cross-sectional epidemiological study from Tromsø, North Norway was to evaluate the relation between blood pressure and serum parathyroid hormone (PTH). 10419 subjects were invited to participate in the fifth Tromsø study and 8128 attended. 7954 subjects had serum PTH measured, and among these, information on blood pressure medication was available in 5841 subjects (2554 males) with serum calcium within the reference range 2.20-2.60 mmol/L. In a multiple linearregression model with age, BMI, serum calcium, serum creatinine, and smoking status as covariables, serum PTH was a significant and positive predictor of systolic and diastolic blood pressure in both genders. When dividing the cohort in PTH quartiles, and adjusting for age, BMI, serum calcium, and serum creatinine, the differences between the lowest and highest PTH quartile in systolic and diastolic blood pressure were 5.0 and 3.5 mmHg for males and 4.1 and 2.5 mmHg for females, respectively. In previous studies we have found serum PTH to be a positive predictor for future increase in blood pressure, and also that the association between serum PTH and blood pressure cannot alone be ascribed to a blood pressure induced increase in urinary calcium excretion. To further elucidate the relation between serum PTH and blood pressure, randomized clinical trials with calcium and/or vitamin D supplementation to subjects with increased serum PTH levels are needed