Vitamin D Levels and Prevalence of Vitamin D Deficiency Associated with Sex, Age, Region, and Season in Koreans

ABSTRACT

BACKGROUND: Although many studies on vitamin D have been conducted, they have not been consistent regarding the method of measurement, the individuals investigated, and the season of blood sampling. Thus, this study was performed to investigate 25-hydroxy vitamin D [25(OH)D] levels and the prevalence of 25(OH)D deficiency by age, region, and season using the standard method for vitamin D measurement. METHODS: A total of 17,252 health examinees (9,180 men and 8,072 women) who were administered the vitamin D test at 16 health promotion centers in 13 cities in Korea from January to December 2013 were selected for this study. Measurements of 25(OH)D2 and 25(OH)D3 were performed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) using the MSMS Vitamin D Kit. RESULTS: The levels of 25(OH)D were significantly lower among women than men. The median 25(OH)D value was lowest among men and women in their 20s when compared to other age groups. We observed the lowest levels in January and February and the highest levels in August, September, and October. The prevalence of 25(OH)D deficiency (having levels of <10 ng/mL) was significantly higher among women than men. When different age groups were analyzed, the highest rates of 25(OH)D deficiency were found in their 20s, and prevalence decreased with age (up to an age of 60 years). Lastly, the prevalence of 25(OH)D deficiency was highest in Seoul and the Gyeonggi area when compared to other regions. CONCLUSIONS: Level of 25(OH)D and the prevalence of 25(OH)D deficiency differed by sex, age, month (season), and region.