Circumpolar adaptation, social change, and the development of autoimmune thyroid disorders among the Yakut (Sakha) of Siberia

Abstract

Objectives:Alterations in thyroid function appear to play a central role in adaptation to Arctic environments. Increased thyroid activity in indigenous circumpolar populations is associated with upregulated metabolism, including elevated basal metabolic rate (BMR); however, little is known about the possible health consequences of these climate-induced changes on thyroid function. The focus of the present study is to determine the prevalence of autoimmune thyroid disorders and their lifestyle and metabolic correlates among a sample of indigenous Yakut adults from northeastern Siberia. Methods: Anthropometric dimensions, health data, and plasma samples were collected among 281 adults (143 women, 138 men; ≥18 years old) from the rural community of Berdygestiakh (62°N, 127°E; pop. 4,900), Sakha Republic (Yakutia), Russia. BMR measurements were available for 96 women and 98 men. Free triiodothyronine (T 3), free thyroxine (T 4), thyroid stimulating hormone (TSH), and anti-thyroid peroxidase antibody (TPOAb) levels were determined using enzyme immunoassay. Results:: Twenty-two percent of women and 6% of men had clinically elevated (>30 IU/ml) TPOAb. TPOAb was positively correlated with TSH (P < 0.01), T 3 (P < 0.05), and T 4 (P < 0.05) in women and showed a positive trend with T 4 (P = 0.06) in men. Monthly household income was significantly positively correlated with TPOAb in men (P < 0.01) and showed a trend among women (P = 0.06). Conclusions:: Although preliminary, these findings document higher than expected TPOAb levels among Yakut women and suggest possible consequences of increased thyroid activity associated with circumpolar adaptation and social change. © 2011 Wiley-Liss, Inc.