title: Seasonal vitamin D status and endothelial function in healthcare workers.
abstract: OBJECTIVE
  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.
  
  
  METHODS
  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.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  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.
authors: Department of Internal Medicine, Faculty of Medicine, Marmara University, İstanbul, Turkey.
authors: Özlem
authors: Ö
authors: Haliloğlu
authors: Department of Biochemistry, Faculty of Medicine, Marmara University, İstanbul, Turkey.
authors: Tolga
authors: T
authors: Kasaci
authors: Department of Endocrinology and Metabolism, Faculty of Medicine, Marmara University, İstanbul, Turkey.
authors: Dilek
authors: D
authors: Yavuz
mesh_terms: D059168:Carotid Intima-Media Thickness; D006282:Health Personnel; D006801:Humans; D010281:Parathyroid Hormone; D012621:Seasons; D014807:Vitamin D / Q000032:analysis*; D014808:Vitamin D Deficiency
chemical_list: D010281:Parathyroid Hormone; D014807:Vitamin D
keywords: 25-hydroxyvitamin D; Vitamin D deficiency; carotid intima media thickness; endothelial function; healthcare worker