Relationship between serum parathyroid hormone, serum calcium and arterial blood pressure in patients with primary hyperparathyroidism: results of a multivariate analysis.

OBJECTIVE

To evaluate the possible relationship between serum calcium, serum parathyroid hormone (PTH) levels and arterial blood pressure (BP) in patients with primary hyperparathyroidism (HPT).

DESIGN

A retrospective population-based study.

METHODS

Charts of 194 patients with proven primary HPT were reviewed, and the main clinical and biochemical parameters were recorded. There were 48 men (24.7%) and 146 women (75.3%), with a median age of 59 years (range 23-82 years). Patients who used antihypertensive drugs or hormone replacement therapy had been previously excluded. All patients underwent successful parathyroidectomy, and were cured of their disease.

RESULTS

There were no differences (P=NS) between men and women in systolic (143.3+/-19.1 vs 145.4+/-17.1 mmHg) and diastolic (87.1+/-12.3 vs 88.4+/-9.9 mmHg) BP, and in the main biochemical parameters. A significant (P<0.01) correlation was found between (i) serum calcium and serum PTH levels (r=0.39, F=88.36), (ii) age and BP, both systolic (r=0.61, F=118.16) and diastolic (r=0.48, F=64.5), and (iii) body mass index (BMI) and BP (r=0.45 and 0.36 respectively). There was no significant association of serum calcium levels with systolic (r=0.0974, t=1.3422, P=0.18) or diastolic (r=0.1117, t=1.5409, P=0.12) BP, and of serum PTH levels with systolic (r=-0.0349, t=-0.4783, P=0.63) or diastolic (r=-0.0793, t=-1.0913, P=0.28) BP. Multivariate analysis confirmed that none of the independent biochemical parameters significantly correlated with BP, both systolic and diastolic.

CONCLUSIONS

In patients with primary HPT there is no relationship between PTH, calcium and BP. Thus, in hyperparathyroid patients, BP should be considered as an independent variable, mainly related to age and BMI.