Introduction:

There are few studies indicating a relationship between vitamin D, parathyroid hormone (PTH), and parameters of endothelial function.

Objectives:

The aim of the study was to establish the relationship between vascular endothelial function and the level of vitamin D and PTH in women with arterial hypertension (AH).

Patients and methods:

It was a cross‑sectional study of 141 women with AH stage II aged 50.8 ±6.0 years. We determined the serum levels of total 25‑hydroxyvitamin D (25(OH)D), PTH, endothelin 1, as well as nitrites and nitrates. Endothelial function was measured by impedance rheography. Endothelium‑dependent vasodilatation was measured by a reactive hyperemia test. Endothelium‑dependent vasodilatation of less than 12% was considered as endothelial dysfunction (ED).

Results:

Vitamin D deficiency was observed in 53 women (37.6%); insufficiency, in 42 (30.1%); and the optimal level, in 46 (32.3%). ED was determined in 49.6% of the patients. The serum PTH level was 36.6 ±20.1 pg/ml, and it was above the upper limit of the reference range only in 5.5% of the cases. We showed significant correlations between PTH and systolic blood pressure (R = 0.28; P = 0.003), PTH and 25(OH)D (R = –0.27; P = 0.025), and 25(OH)D and SBP (R = –0.23; P = 0.034). In the group with ED, the serum level of endothelin 1 was higher compared with the group without ED (0.57 ±0.18 vs. 0.49 ±0.21 pg/ml; P = 0.032) and that of nitrates and nitrites was lower compared with the group without ED (15.2 [11.1–29.9] vs. 22.8 [16.9–33.0] μmol/l; P = 0.0005). In the group without ED, PTH

inversely correlated with endothelin 1 (R = –0.27; P = 0.043). In the group with ED, PTH inversely correlated

with nitrates and nitrites (R = –0.48; P = 0.003).

Conclusions:

In women with AH and without ED, PTH affected the production of a vasoconstrictor, endothelin 1, while in those with ED, PTH was associated with a lower production of vasodilators, nitrates and nitrites, by the  vascular endothelium.