This retrospective study aimed to determine the levels of 25- hydroxyvitamin D [25-(OH) D] in the individuals that have been referred to two laboratories (Bio Lab and King Lab) and to around 50 private side laboratories that use both Bio Lab and King Lab as a referral lab for their tests, in Erbil city, Iraq. Then show the range of deficiency and its relation with sunlight exposure, sex and age. Out of the total number of cases (N=10823), large percentage (nearly 78%) referred to both clinical laboratory based in Erbil city were found to have a deficiency in vitamin D levels, which means they had 25-(OH) D levels lower than 20 μg/L. This study found the percentage of vitamin D level in the serum of groups insufficient, deficient, adequate, optimal; intoxication were 52.8, 24.1, 11, 12 and 0.2% respectively. When the records have been compared according to gender, the results suggested that there was no difference between male and female within the study population (P>0.05), while there was difference in the grouped ages (P<0.05). Our results indicate that although Erbil is located in a Mediterranean country, people living there should periodically check their 25-(OH) D levels, in order to get appropriate supplements of vitamin D, which eventually prevents secondary chronic disease due to vitamin D deficiency.
25-hydroxyvitamin D deficiency; Seasonal variations; Vitamin D.