Gender differences in the content of thyroid hormones in different groups of the population of the Arctic

The study of the gender characteristics of the thyroid gland functional activity take on particular significance in light of the increasing frequency of detecting various thyroid dysfunctions, especially in the Northern regions. Aim: to carry out a comparative analysis of the thyroid profile due to sex, taking into account the population groups of the North. Materials and methods. We examined 338 people born and living or wandering near the villages in the Arctic zone of the Russian Federation. The examined persons were divided by gender (men, women), age (21-44; 45-59 years) by gender and, population group (nomadic aborigines, sedentary aborigines, local Caucasoid population). The serum levels of thyroid hormones were determined by the method of enzyme immunoassay. Results and discussion. Analysis of sex differences in thyroid status by age groups showed a higher thyrotropin level in women of different age groups (p = 0.049; p = 0.048) compared with men (1.94 and 2.08 μIU/L and 1.60 and 1,81 μIU/L, respectively). In addition, in the age group 21-44 years, there was an increase in thyroxine level (107.31 and 97.70 nmol/L, p <0.001) and a decrease in the content of free triiodothyronine in women (4.79 and 5.36 pmol/L, p = 0.002) compared to men. There were shown a higher content of thyrotropin and thyroxine in the female aboriginal population compared with the male population. A higher level of thyroxine in women may be due to its reserve functions in relation to free fractions of iodothyronines, which play an important role in the reproductive health of women. The lower content of free fractions of triiodothyronine and thyroxine was shown in women belonging to the local Caucasoid population compared with men. Free fractions of thyroxine were lower in women - sedentary aborigines in relation to men of this group. The higher content of free fractions of iodothyronines in men may be due to longer-term effects from cold temperatures when working outdoors. Conclusion. Consequently, gender differences in the content of thyroid hormones among the local Caucasoid population are in the content of free fractions of iodothyronines, while the indigenous population has differences in the content of thyrotropin and total fractions of thyroxine. The sedentary aboriginal population, in addition to its own distinctive features characteristic, acquires the characteristics of the Caucasoid population with distinctive gender characteristics according to the free fractions of iodothyronines.

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