Reports in Thyroid Research

The Effect of Vitamin D Replacement on Subjects with Subclinical Hypothyroidism and Vitamin D Deficiency

Abstract

Naji J Al Johani, Mohd S Ansari, Salma Hussein, Mussa H Almalki, AL Mohareb Ohoud, Saad Al Zahrani, Shawana Z Khan, Fatima Almousawi, Awad Al Shahrani and Imad Brema

Objectives: There is a known inverse association between serum vitamin D level and Hashimotos thyroiditis from observational studies, however, very few interventional studies explored the effect of replacing vitamin D on the course of the disease. The aim of this study was to assess the effect of vitamin D replacement on serum thyroid autoimmunity, thyroid stimulating hormone (TSH), free T4 (FT4) in subjects with both autoimmune subclinical hypothyroidism (SCH) and Vitamin D deficiency.

Methods: We assessed the effect of vitamin D3 replacement on sixty-four Saudi patients with SCH (defined as TSH>4.2 but less than 10 mIU/L) and vitamin D deficiency (defined as plasma level<50, nmol/L). We measured TSH, FT4, anti TPO antibody titer (Anti TPO) and vitamin D levels at baseline and 3 months after supplementation of Cholecalciferol at a weekly oral dose of 50,000 IU.

Results: The mean age of the participants was 40.0 ± 1.8 years, mean body mass index was 29.2 ± 0.6 kg/m2 and 64.7% of the participants were females. Mean TSH was 6.1 ± 0.3 mIU/L, mean FT4 was 14.5 ± 0.2 pmol/L, mean anti TPO level was 230.6 ± 96 IU/L and mean vitamin D level was 38.9 ± 3.6 nmol/L. Following 3 months of Cholecalciferol, serum 25 (OH) Vitamin D significantly increased to 62.1 ± 3.7 nmol/L, p<0.001, while TSH significantly decreased to 4.9 ± 0.26 mIU/L, p<0.001. There was a 64% reduction in anti TPO level which was negatively correlated with vitamin D level at baseline, r=-0.433, p=0.034.

Conclusion: Replacing vitamin D in Saudi subjects with mild autoimmune SCH and vitamin D deficiency significantly reduced serum TSH and improved thyroid autoimmunity. However, larger, randomized, controlled clinical trials for longer duration are needed to clarify the role of vitamin D replacement on the remission of mild SCH.

PDF