Retrospective evaluation of 25 hydroxy vitamin D levels and related factors measured in a tertiary hospital

Introduction and Aim: Vitamin D has an important role due to its regulatory effects on metabolism, especially on the skeletal system. The aim of this study was to evaluate factors affecting 25 hydroxy vitamin D (25(OH)D) levels like gender, age and season, in relation with parathormone (PTH) and calcium. Materials and Methods: 12484 cases over the age of 18 whose 25(OH)D levels were measured between January 1, 2022 and December 31, 2022 at Ondokuz Mayıs University Hospital were included in the study. 1912 cases with simultaneous PTH and calcium tests were also evaluated. These cases were categorized according to gender, age and seasonal groups in which 25(OH)D was measured, and 25(OH)D, PTH and calcium levels were compared among the groups. In addition, the correlation between 25(OH)D levels and other parameters was examined. Results: Gender distribution of 12484 cases whose 25(OH)D levels were screened was as follows: 9578 (76,7%) females and 2906 (23,3%) males. 25(OH)D levels were similar in men and women (p=0,058). When seasonal differences in vitamin D were evaluated, 25(OH)D levels were found to be lower in winter than in summer (p<0,001). The 25(OH)D levels were lower in the group below 65 years of age than in the groups 65-74 and above 75 years old (p<0,001). PTH levels were higher in women than in men (p=0,002). PTH levels were different among the age groups, highest in the group above 75 and lowest in the group below 65 years (p<0,001). There was a weak positive correlation between 25(OH)D and calcium and a weak negative correlation between 25(OH)D and PTH. Conclusion: In this study, it was determined that a significant proportion of 25(OH)D levels measured in our hospital during a one-year period were measured in women. Although PTH is higher in women and in older groups, 25(OH)D levels are similar in women and men and higher in elderly groups. These findings suggest that elderly groups may be taking more vitamin D supplementation or treatment.