Seasonal vitamin D status and endothelial function in healthcare workers

Healthcare workers have long working hours indoors and are at risk of vitamin D deficiency. The aim of this study was to determine seasonal vitamin D status and its relationship with early atherosclerotic markers, endothelial function, and carotid intima-media thickness (CIMT) in healthcare workers of Marmara University Hospital, İstanbul.

One hundred and ninety healthy volunteer healthcare workers and 66 nonmedical volunteers of Marmara University Hospital were included in the study and 25-hydroxyvitamin D (25(OH)D), calcium, intact parathyroid hormone (PTH), endothelial function, and CIMT were measured twice during winter and summer seasons.

Mean vitamin D levels were 20 ng/mL in summer and 16.4 ng/mL in winter. Out of the healthcare workers, 48.9% were vitamin D deficient at the end of summer and 71.5% in winter. Flow-mediated dilation (FMD) values were similar in both groups in both seasons; however, FMD values of 64 healthcare workers in summer were significantly higher than in winter. Serum 25(OH)D was positively associated with FMD (r = 0.1797, P = 0.0441) and negatively correlated with serum PTH (r = -0.2459, P < 0.0001). A negative correlation between FMD and serum PTH (r = -0.1757, P = 0.0473) was observed.

Vitamin D levels of healthcare workers are very low, even in summer time. Healthcare workers must be considered a group at major risk for vitamin D deficiency.