Evaluation of vitamin D status and the relationship with thyroid disease

INTRODUCTION: Vitamin D is known to be an essential element for calcium metabolism and bone health. Recent studies have also identified vitamin D deficiency as a risk factor for cancers, autoimmune diseases, and cardiovascular disorders. The aim of this study was to investigate the relationship between vitamin D status and thyroid disease.
METHODS: A total of 1197 adults aged 18-45 years were enrolled in this retrospective study. Data of serum levels of vitamin D, free triiodothyronine, free thyroxine, and thyroid-stimulating hormone were retrieved and analyzed. The individuals were divided into 3 groups: euthyroid state (n=940), hypothyroidism (n=206), and hyperthyroidism (n=51). The vitamin D status of the groups was compared.
RESULTS: The study population had a mean serum vitamin D concentration of 18.33±14.53 ng/mL. The mean vitamin D level was 16.01±14.37 ng/mL in females (n=921) and 26.04±12.26 ng/mL in males (n=276) (p<0.001). The mean vitamin D level in the euthyroid, hypothyroidism, and hyperthyroidism groups was 8.79±15.04 ng/mL, 15.72±11.71 ng/mL, and 20.4±14.23 ng/mL, respectively. There was a statistically significant difference in the vitamin D level between the hyperthyroidism and hypothyroidism groups (p<0.05).
DISCUSSION AND CONCLUSION: Vitamin D deficiency/insufficiency is an important public health problem in Turkey, especially in females. The hypothyroid patients had significantly lower vitamin D levels compared with the other groups. Vitamin D supplementation may be considered in the treatment of thyroid disease; however, additional prospective studies with a larger number of subjects are needed.