Impaired flow-mediated vasodilation of the brachial artery in patients with primary hyperparathyroidism improves after parathyroidectomy

Objective: The endothelium is a newly recognised target tissue of parathyro id hormone (PTH). It is not clear whether hyperparathyroidism affects endot helial function and whether parathyroidectomy (Ptx) has an influence on art erial vessel wall properties. We studied brachial flow-mediated vasodilatio n (FMD) and brachial and carotid intima-media thickness (IMT) in patients w ith primary hyperparathyroidism (pHPT) before and after Ptx and in healthy controls. Methods: 19 patients with pHPT (mean+SEM, age 45+/-4.7 years, PTH 238+/-52 ng/l) were studied. Diabetes, hypertension and vascular disease w ere excluded. Twenty healthy volunteers matched for age, sex and blood pres sure served as controls. Enddiastolic diameter, FMD and nitroglycerine-indu ced (NMD) dilation of the brachial artery were measured by a multigate puls ed doppler system (echo-tracking), IMT was determined using automatic analy sis of the M-line signal. Healthy volunteers where studied on one occasion, patients were studied at baseline and 6 months after Ptx. Results: Six mon ths after Ptx PTH had decreased to normal, blood pressure levels remained u nchanged. Endothelium dependent FMD at baseline was impaired in patients co mpared to controls (4.7+/-1.2 vs. 18.2+/-3.7%, P<0.01), however, FMD improv ed significantly after Ptx (16.7+/-3.0%, P<0.01). Nitroglycerine-induced di lation, IMT and artery diameter were not different between groups and did n ot change after Ptx. Conclusions: Impaired endothelium dependent vasodilati on in patients with primary hyperparathyroidism improves after successful p arathyroidectomy. Endothelial dysfunction associated with primary hyperpara thyroidism occurs without detectable structural wall alterations of the bra chial artery and appears therefore to be an early and reversible arterial a lteration. (C) 2000 Elsevier Science B.V. All rights reserved.