Vitamin D Status Across Age Groups in Turkey: Results of 108,742 Samples from a Single Laboratory

What is already known on this topic? The extra-skeletal effects of vitamin D have caused an increase in interest in vitamin D. This interest has led to an increase in requests for serum 25-hydroxyvitamin D (25-OHD) levels. Previous reports have suggested a high prevalence of vitamin D deficiency in Turkey. Furthermore, high dose vitamin D treatment has been prescribed, even in cases with normal 25-OHD levels, in order to obtain some of the extra-skeletal effects of vitamin D. What this study adds? This study with a very large sample size aimed to assess vitamin D status in Turkey. Data from this study do not support the idea of a vitamin D deficiency pandemic in Turkey. Successful implementation of the vitamin D supplementation program appears to have overcome vitamin D deficiency for those under 1-year of age in Turkey Objective: The aim was to determine vitamin D status in the general population in Turkey between 2011 and 2016, and to evaluate the effectiveness of the national vitamin D supplementation programme. Methods: Serum 25-hydroxyvitamin D (25-OHD) measurement data were retrieved from an internationally accredited laboratory, operating nationwide. A total of 108,742 measurements of 25-OHD were analyzed using the cut-off values of 0-11 ng/mL, 12-19 ng/mL, 20-49 ng/mL, 50-70 ng/mL and >70 ng/mL for vitamin D deficiency, insufficiency, sufficiency, possibly harmful and excess respectively. Results: The mean[+ or -]standard deviation 25-OHD level was 21.6[+ or -]13.3 ng/mL. Mean 25-OHD concentrations by age groups were: 37.3 ng/mL, 30.1 ng/mL and 23.7 ng/mL for