Endothelial vasodilatory dysfunction in primary hyperparathyroidism is reversed after parathyroidectomy

Area of Science:

• Cardiovascular Medicine
• Endocrinology
• Vascular Biology

Background:

• Primary hyperparathyroidism (HPT) is linked to hypertension and increased cardiovascular mortality.
• Endothelial dysfunction, characterized by impaired endothelium-dependent vasodilation (EDV), is known in hypertension but understudied in HPT.
• Parathyroid hormone's vasoactive properties suggest a potential role in HPT-related vascular disturbances.

Purpose of the Study:

• To investigate endothelium-dependent and independent vasodilation in patients with primary hyperparathyroidism.
• To assess whether parathyroidectomy normalizes endothelial function in HPT patients.
• To evaluate potential early markers of atherosclerosis, such as carotid intima-media thickness, in HPT.

Main Methods:

• Forearm venous occlusion plethysmography was used to measure EDV and endothelium-independent vasodilation (EIDV) in 25 HPT patients and 25 controls.
• Local infusions of methacholine and nitroprusside assessed EDV and EIDV, respectively.
• Ambulatory blood pressure and carotid intima-media thickness were measured; endothelial function index was calculated.

Main Results:

• HPT patients exhibited a significantly lower endothelial function index compared to controls (P = .003).
• Ten months post-parathyroidectomy, the endothelial function index normalized (P = .01), with improved EDV and reduced EIDV.
• Carotid intima-media thickness and blood pressure remained similar between groups and were unchanged after surgery.

Conclusions:

• Endothelial vasodilatory dysfunction is a significant vascular complication of primary hyperparathyroidism.
• Parathyroidectomy is an effective treatment for normalizing endothelial dysfunction in HPT.
• These findings highlight endothelial dysfunction as a key vascular disturbance in HPT that is reversible with treatment.