Relationship of Vitamin D Status with Thyroid Autoimmunity in New Onset Autoimmune Hypothyroidism.

Background: Study of serum vitamin D level in new onset hypothyroid patients and its correlation with thyroid related parameters and antibody titers.

Objectives: We aimed to compare serum vitamin D level in new onset hypothyroid patients versus controls. Furthermore we evaluated for any association of vitamin D status with hypothyroid state and its correlation with various thyroid related parameters.

Methodology: In this cross sectional study , 61 new onset hypothyroid subjects (cases) and 40 age, sex and BMI matched healthy individuals (controls) were recruited. Measurements of serum vitamin D, thyroid hormones, thyroid peroxidase antibody (TPO-Ab), parathyroid hormone (PTH), calcium and phosphorus were done for all study participants.

Results: The mean serum vitamin D in cases (22.95±8.59 ng/ml) was significantly lower than the controls (27.9±7.85 ng/ml) (p<0.01). The prevalence of vitamin D deficiency was significantly higher among hypothyroid subjects than controls (p=0.009). Hypothyroid subjects with vitamin D deficiency group had significantly higher TSH level, greater thyroid volume and elevated anti TPO titres than those with vitamin D sufficiency. Serum vitamin D level had significant inverse correlation with anti TPO-Abtiters even after adjustment for age, sex and BMI.

Conclusion: Serum vitamin D is significantly low in new onset hypothyroid patients than healthy controls. Hypothyroid patients with vitamin D deficiency have significantly higher TSH, antibody titres and thyroid volume. A significant negative correlation was observed between serum vitamin D leveland anti TPO titres. Moreover, serum vitamin D remained an independent predictor of TPO level among hypothyroid subjects.