SEASONAL VARIATION OF VITAMIN-D LEVELS IN THE ADULT POPULATION IN ISTANBUL/TURKEY: A POPULATION-BASED STUDY

Abstract

Objective: The current research examined if there is a variance in the frequency of vitamin D deficiency or insufficiency among adults visiting the hospital for medical problems in winter and summer, and whether comorbidities have an impact on this. Material and Method: A total of 1155 patients (771 women, 384 men, mean age:48±15 years) who were admitted to the outpatient clinics of Istanbul Medeniyet University Goztepe Training and Research Hospital in August and February were tested for 25(OH)D levels for any reason were included. A 25(OH)D level of<20 ng/ml was stated as inadequacte, and 20–29 ng/ml was defined as insufficient. The two groups were examined in contrast in terms of vitamin D deficiency and insufficiency and the frequency of comorbidities. Results: 25(OH)D levels were inferior in the winter compared to the summer (16.1±12.5 ng/ml versus 22.2±15.8 ng/ml, p<0.001). Vitamin D deficiency was detected in 769 (66.6%) patients, and vitamin D insufficiency was detected in 226 (19.6%). Furthermore, 51.9% and 78.6% of patients had vitamin D deficiency (p< 0.001) and 27.3% and 13.1% had vitamin D insufficiency (p<0.001) during summer and winter, respectively. Prevalence rates of diabetes (60.1% and 39.9%, respectively, p=0.04) and hypertension (62.7% and 37.3%, accordingly, p<0.01) were more common in the winter compared to the summer. Conclusion: The findings of this research show that vitamin D insufficiency and deficiency are well-known health issues in Turkey, and although there has been some improvement, the problem persists even during the sunny seasons.