VITAMIN D THERAPY IMPROVES THYROID FUNCTION AND AUTOIMMUNITY IN HASHIMOTO THYROIDITIS - ONE OF THE FIRST DOUBLE-BLIND PLACEBO-CONTROLLED RCT IN A TERTIARY CARE HOSPITAL IN SOUTH ASIA

Abstract

Objective: Extra-skeletal benefits of 25hydroxy vitamin D in other autoimmune diseases are well known, but its role in
autoimmune thyroiditis is yet to be proved in vivo, though an association was suggested by different studies. We aimed to
show the beneficial impact of vitamin D therapy in the pathogenesis of this disease even without levothyroxine
supplementation.
Design: A randomized double-blinded placebo-controlled trial.
Patients: 140 patients of subclinical autoimmune thyroiditis chosen by purposive sampling randomized in two groups:
intervention and placebo, were weekly given 60000 units of cholecalciferol or placebo for eight weeks, followed by
monthly for six months.
Measurements: Done as follows: 25 hydroxy vitamin D (ng/ml), free tetraiodothyronine (ng/dl), thyroid stimulating
hormone (mIU/ml), thyroid peroxidase, thyroglobulin antibodies (IU/l).
Results: Decline in thyroid stimulating hormone (mean ± standard error 6.26 ± 0.39 mIU/ml to 3.23 ± 0.24 mIU/ml),
thyroglobulin antibody (mean ± standard error 246.2 ± 124.3 IU/l to 69.74 ± 27.22 IU/l), rise in free tetraiodothyronine
(mean ± standard error 1.039 ± 0.02 ng/dl to 1.243 ± 0.05 ng/dl) at end of six months of cholecalciferol therapy observed
in a part of the intervention group (named 'responders') compared to placebo.
Conclusion: One of the earliest studies in South East Asia that unveiled a robust association of 25OH vitamin D therapy
and thyroid function. The overall intervention group did not reach statistical significance. The reason why some patients
are more likely to respond to cholecalciferol therapy while some do not, is unknown and needs further research. Overt
cases of hypothyroidism were excluded.
The RCT is registered with www.ctri.nic.in, registration number CTRI/2017/05/008596.