This retrospective study aimed to determine the levels of 25-hydroxyvitamin D [25-(OH) D] in the individuals that has been referred to both laboratories (Bio Lab and King Lab) and to around 50 private side laboratories that they use both Bio Lab and King Lab as a referral lab for their tests, Within Erbil City-IRAQ. Then show the range of deficiency and its relation with sunlight exposure, sex and age. From the total participated patients (N=10823) cases, large percentage (nearly 78 %) referred to both clinical laboratory based in Erbil city were found to have a deficiency in the vitamin D levels, which means they 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 and intoxication were 52.8, 24.1, 11, 12 and 0.2 % respectively. When the records compared based on 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, the people living in Erbil city should check their levels of 25-(OH)D periodically. 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.