Presenter : Vimal Balu
Mentor : Josh Snodgrass
Major : Biology, Anthropology
Northern populations physiologically adapt to extreme cold by upregularing basal metabolic rate. The thyroid appears central to this adaptation. Thyroid hormones regulate metabolic responses to chronic cold among indigenous Arctic populations. However, it is un- clear whether this adaptation among circumpolar groups predisposes them to autoimmune thyroid disorders (AITDs). This study ad- dresses this question by examining correlates of seasonal variation in anti-thyroid peroxidase antibody (TPOAb) concentrations among the Yakut of Siberia. Anthropometric and biomarker data were obtained on two occasions (Summer 2009 and Winter 2011) on a sample of Yakut men (n=52) and women (n=88) (≥18 years old). TPOAb levels are higher in summer than winter in both men (P<0.01) and women (P<0.05). Women have significantly higher TPOAb levels than men (P=0.05), and are more likely to have an AITD (28% of women versus 4% of men; TPOAb >30 IU/mL). TPOAb concentrations are associated with several anthropometric dimensions among men (negative trends with weight [P=0.08]). Finally, changes in TPOAb showed a positive trend association with change in thyroid stimulating hormone (TSH; P=0.06) among men, but among women change in TPOAb was negatively associated with change in HDL cholesterol and showed a positive trend with change in triglycerides (P=0.1) and hemoglobin (P=0.08). This study documented impor- tant sex differences in AITD risk among the Yakut, and an unexpected drop in TPOAb levels between summer and winter.