FRI543 Effect Of Vitamin D Replacement On Thyroid Autoimmunity And thyroid Functions In Subclinical Hypothyroid And Vitamin D Deficient Patients: A Randomized Controlled Trial

Disclosure: N.J. Aljohani: None. Background: Vitamin D status has been implicated to influence several non-skeletal diseases including diabetes, cardiovascular diseases, and auto-immunity. Several observations have also associated vitamin D deficiency with thyroid disorders, but prospective data is lacking. In this randomized clinical trial, we aimed to determine whether vitamin D correction improves subclinical hypothyroid status of Arab adult patients. Subjects and Methods: A total of 84 subjects with subclinical hypothyroidism were recruited and allocated (1:1) to receive either vitamin D 50,000 IU weekly in first four months (cases) or placebo (Vitamin D 5000 IU weekly). Thyroid function and thyroid autoantibodies was repeated after 3 and 6 months with vitamin D level to see sufficient vitamin D replacement status. Results: Post-intervention, 31 cases and 37 controls completed the intervention. Cases had a significant increase in 25(OH)D levels after 3 and 6 months of intervention. In both cases, and controls, there was a significant decrease in TSH over time (p<0.05), with no significant changes in both circulating FT4 and FT3 levels. A significant decrease in TPO ab and anti-TG ab levels after 6 months (p<0.05) were observed only in cases. In conclusion, vitamin D correction modestly improves thyroid status of Arab patients with known subclinical hypothyroidism. Further investigations are needed as to whether vitamin D supplementation is more beneficial among subclinical hypothyroid patients who were deficient at baseline. Presentation: Friday, June 16, 2023