Effects of sun exposure and dietary vitamin D intake on serum 25-hydroxyvitamin D status in hemodialysis patients

BACKGROUND/OBJECTIVES: Vitamin D deficiency is common in hemodialysis patients. The aim of this study was to identify whether or not sun exposure and dietary vitamin D intake have effects on serum 25-hydroxyvitamin D (25(OH)D) status in hemodialysis (HD) patients. The objective was to identify the main determinants of serum vitamin D status in the study subjects. SUBJECTS/METHODS: A cross-sectional study of 47 HD patients (19 males and 28 females) was performed. We assessed serum 25(OH)D and 1,25(OH)2D levels between August and September 2012 and analyzed the prevalence of vitamin D deficiency in HD patients. To evaluate the determinants of serum 25(OH)D levels, we surveyed dietary vitamin D intake, degree of sun exposure, and outdoor activities. To compare biological variables, serum 25(OH)D was stratified as below 15 ng/ml or above 15 ng/ml. RESULTS: Mean 25(OH)D and 1,25(OH)2D levels were 13.5 + - 5.8 ng/ml and 20.6 + - 11.8 pg/ml, respectively. The proportions of serum 25(OH)D deficiency ( 15 ng/ml), insufficiency (15- 30 ng/ml), and sufficiency (¡Ã 30 ng/ml) in subjects were 72.4%, 23.4%, and 4.3%, respectively. Prevalence of vitamin D deficiency in female patients was 78.6%, whereas that in males was 63.2% (P