Studies on flow-mediated vasodilation and intima-media thickness of the brachial artery in patients with primary hyperparathyroidism

The endothelium is a newly recognized target organ of parathyroid hormone (PTH) and may contribute to its effects on vascular tone and blood pressure regulation. Flow-mediated vasodilation (FMD), brachial and carotid intima-media thickness (IMT) were studied in patients with primary hyperparathyroidism (pHPT) and controls to evaluate endothelial function and structural arterial vessel wall alterations. Sixteen patients with pHPT (mean ± SEM, age 44 ± 5 years; PTH 229 ± 72 ng/L; serum calcium 3.0 ± 0.06 mmol/L; serum phosphate 2.0 ± 0.2 mg/L) and 16 normocalcemic control subjects matched for age, sex, and blood pressure were included. Diabetes, hypertension, and vascular disease were excluded in both groups. End-diastolic diameter, flow-mediated (FMD) and nitroglycerin-mediated (NMD) dilation of the brachial artery were measured by a multigate pulsed Doppler system (echo-tracking). IMT was determined using automatic analysis of the M-line signal. Endothelium-dependent FMD was impaired in patients compared to controls (4.6 ± 1.6% v 19.2 ± 3.9%, P< .001). NMD (23.8 ± 3.1% v. 22.4 ± 2.8%, P = NS), carotid and brachial IMT (0.60 ± 0.04 mm v 0.64 ± 0.06 mm, P = NS, and 0.46 ± 0.04 mm v 0.47 ± 0.08 mm, P = NS, respectively) and artery diameters were not different. Endothelium-dependent vasodilation is impaired in patients with primary hyperparathyroidism despite normal IMT. Endothelial dysfunction may contribute to increased cardiovascular morbidity and mortality in pHPT.