Objective: The purpose of this study was to determine whether vitamin D deficiency is present in patients admitted to our hospital and investigate if there is any difference between 25-OH Vitamin D levels according to age, gender and seasons.

Material and Method: 25-OH vitamin D levels of 12389 patients who are between 18-70 years of age admitted to Elazığ Fırat University between January-December 2014 were investigated retrospectively. Patients with vitamin D levels >80 ng/ml were excluded from the study. Serum 25-OH D levels <12 ng/ml is accepted as severe insufficiency, 12-20 ng/ml mild to moderate insufficiency, 21-30 ng/ml deficiency, and >30 ng/ml is sufficiency.

Results: The study consisted of 10498 females (85%) and 1891 males (15%). The mean 25-OH D levels were 14.61±13.43 ng/ml in female and 16.81±10.29 ng/ml in male. Vitamin D levels showed a significant differences in both male and female patients between age groups (p<0.001). 25- OH D levels were found as the lowest in winter, and the highest in summer in both females and males. Statistically significant difference between seasons were observed (p<0.001). Severe insufficiency (<12 ng/ml) level of vitamin D was found as 59% in females, 36% in males, while insufficiency (<20 ng/ml) level of Vitamin D was at 78% in female, and 73% in male.

Conclusion: In this study, in patients who admitted from Elazığ and nearby cities to our hospital serious vitamin D deficiency was detected. Vitamin D-enriched foods or vitamin D supplementation are becoming more important when considering that the deficiency of vitamin D is accompanying many of the important diseases.