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; ¡Ý18 years old) from the rural community of Berdygestiakh (62¡ãN, 127¡ãE; pop. 4,900), Sakha Republic (Yakutia), Russia. BMR measurements were available for 96 women and 98 men. Free triiodothyronine (T3), free thyroxine (T4), 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