ReviewVitamin D deficiency: A single centre analysis of patients from 136 countries

- Vitamin D [25(OH)D] concentrations of 60,979 patients from 136 countries were measured in a single laboratory.
- Serum 25(OH)D (total) measurements showed 82.5% of the studied patients have vitamin D deficiency to insufficiency. 26.4% of females and 18.4% of males have extreme deficiency of 25(OH)D.
- The prevalence of hypovitaminosis D is significantly high among population of UAE, Saudi Arabia and many Middle Eastern countries, especially among women, despite abundant sunshine.
- 86.1% UAE nationals and 78.9% visitors of other nationalities were found <75 nmol/L of 25(OH)D. 28.4% of UAE nationals and 17.5% of visitors of other nationalities have extreme deficiency of 25(OH)D.

Vitamin D deficiency is a global problem, thought to be related to lack of sunlight exposure, and usually accompanied by reduced dietary intake. This study was designed to determine vitamin D status of 60,979 patients admitted to the Burjeel Hospital of VPS healthcare in Abu Dhabi, United Arab Emirates (UAE) from October 2012 to September 2014. The total concentrations of vitamin D [25(OH)D] of all the studied patients were measured in a single laboratory. Of the studied patients, 57.5% were female and 42.5% were male. Serum 25(OH)D (total) measurements showed 82.5% of the studied patients have vitamin D deficiency to insufficiency. 26.4% of females and 18.4% of males have extreme deficiency of 25(OH)D. There was higher variability of vitamin D in group of females then males according to coefficient of variation. In our studied cohort teenagers (13-19 years) have shown the lowest levels of serum vitamin D (data not shown and will be communicated as a separate publication). The prevalence of hypovitaminosis D is significantly high among population of UAE, Saudi Arabia and many Middle Eastern countries, especially among women, despite abundant sunshine. 86.1% UAE nationals and 78.9% visitors of other nationalities were found <75 nmol/L of 25(OH)D. 28.4% of UAE nationals and 17.5% of visitors of other nationalities have extreme deficiency of 25(OH)D. Our results are significant, as all of our patients are residing permanently in the UAE or visitors that has yearlong sunlight. In addition, measuring 25(OH)D concentrations in a single laboratory minimized test level variations. Our current study formed the basis of further studies to determine if vitamin D deficiency and insufficiency can aggravate systemic diseases, including hypertension, diabetes or obesity that are also wide-spread in the Middle Eastern region.

The frequency distribution of 25(OH)D concentrations are shown as a skewed distribution, and most of the values are less than 50 nmol/L. Skewness right distribution of 25(OH)D concentration of patients with median of 42.25 nmol/L. For variables normality was tested by Anderson-Darling test. The null hypothesis was rejected on significance level of alpha 0.05, that's why non-parametric test was used. Genders in result value of 25(OH)D were tested by two-tailed Mann-Whitney test. Gender affected the result value of 25(OH)D, with a statistically significant difference between male and female (Sig. = 0.000).83