High serum parathyroid hormone and calcium are risk factors for hypertension in Japanese patients

Excess parathyroid hormone (PTH), known as primary hyperparathyroidism (pHPT), results in hypercalcemia and bone loss. Recent studies have shown that PTH is associated with the occurrence of hypertension in Western countries; however, controversy remains regarding high serum levels of PTH and calcium as risk factors for hypertension in Japanese patients. We retrospectively enrolled 114 consecutive Japanese patients who visited our hospital for examination and treatment of hypercalcemia and/or hypertension with serum calcium levels >= 9.8 mg/dL. To estimate the prevalence of hypertension, the patients were categorized according to calcium levels into hypercalcemic (10.2-13.4 mg/dL) and normocalcemic (9.8-10.1 mg/dL) groups, which were further categorized into high PTH (50-440 pg/mL) and low PTH (8-49 pg/mL) groups. The prevalence of hypertension was higher in patients with hypercalcemia than in patients with normocalcemia in both the high and low PTH groups. The prevalence of hypertension was higher in patients with high serum PTH levels than in patients with low serum PTH levels in both the hypercalcemic and normocalcemic groups. Logistic multiple regression analysis determined that serum calcium (P < 0.05) and PTH (P < 0.01) levels were positive contributors to hypertension. In conclusion, high serum levels of PTH and calcium are risk factors for hypertension in Japanese patients.