Objective: Vitamin D, which is taken by foods as well as synthesized in the body, has important functions in many parts of the organism. As vitamin D is shown to take part in many vital mechanisms, the importance of the molecule is increasing and consequently the workload of clinical laboratories is also increasing. It has been reported that vitamin D level is found to be at deficient scale in populations.

Since age, gender as well as seasons were suggested to affect vitamin D levels, we aimed to evaluate vitamin D test results, which were measured in our laboratory according to the factors mentioned above.

Materials and Methods: The test results of the people, who were admitted to our hospital’s outpatients clinics between January 2013 and December 2014, were obtained from the Laboratory Information Systems, retrospectively. The patients were divided into 3 groups according to their ages being <30 years old, 30-60 years old and >60 years old. Four groups were created according to their vitamin D levels being <10 ng/mL, 10-20 ng/mL, 20-30 ng/mL and >30 ng/mL and two groups according to the season that the measurement was done. Non parametric tests were perofrmed with SPSS 21.0 program as the distributions of the groups were not normal and p values <0.05 were accepted as significant.

Results: The mean age of 8161 people (1168 male, 6993 female) in study group was found to be 56.2±17.3 years. The mean vitamin D level of the group was 18.6±10.9 ng/mL. Vitamin D levels of the female group were lower when compared to male group (p<0.05). The ratio of the people having normal levels of vitamin D was 11.3% (n=926). It was also determined that seasons have an effect on vitamin D levels and vitamin D levels were higher in the oldest group.

Conclusion: Likewise the world, Vitamin D levels were also low in our study. The low levels of vitamin D in Turkey, which is a sunny country, is an indication of deficiency in making use of the sun. The instruction of people to benefit better from the sun, which is a free source of vitamin D, is very important.