Endocrine Abstracts

Vitamin D is a lipid-soluble hormone found in certain foods and synthesized from precursors in the skin when exposed to ultraviolet light. Vitamin D plays a critical role in bone metabolism and many cellular and immunological processes; and low levels have been associated with several chronic and infectious diseases. Vitamin D status is assessed by measuring the concentration of serum 25-hydroxy vitamin D (25(OH) D). Vitamin D deficiency is reported to be common worldwide, but little has been reported about the vitamin D status of adults in Turkey. In this cross-sectional study, we determined the prevalence of 25(OH) D deficiency in adults residing in a city in the Aegean region of Turkey.

A survey was conducted on a representative sample of adults over 20 years old in a non-coastal city. Of the 209 households selected by random sampling, 8.6% (n=18) were unoccupied and 21.5% (n=45) refused to participate. Questions about medical history, vitamin supplementation, sunlight exposure, and dietary vitamin D intake were asked by face to face interview to 391 adults living in the remaining households. Blood samples of the study population were taken once during the winter (n=391) and again during the summer (n=95).

The mean serum 25(OH) D concentration in winter was 16.9±13.1 ng/ml, with 74.9% of the subjects having 25(OH) D deficiency (<20 ng/ml), 13.8% having insufficiency (20–29.99 ng/ml), and 11.3% of the subjects having a sufficient 25(OH) D concentration (≥30 ng/ml). In the summer, the mean serum concentration was 12.6±8.5 ng/ml, with 84.2% having deficiency, 10.5% insufficiency, and 5.3% sufficient levels of 25(OH) D. Deficiency of 25(OH) D was more common among females (78.7%) compared to males (66.4%, P<0.05).

In conclusion, adults living in an urban, non-costal setting in Turkey have a high incidence of vitamin D deficiency.