Thyroid Disorders and Serum Selenium Levels in a Southwestern Nigerian Population

Background/Objective: Thyroid hormones are central to the regulation of energy expenditure and homoeostasis. An important microelement required for the optimal function of the thyroid gland is selenium. The question of whether Nigerian patients with thyroid disorders are deficient in selenium is what this study aims to answer. Methods: This was a comparative cross-sectional study carried out at a tertiary hospital in Southwest Nigeria. Fifty individuals with various thyroid disorders who gave consent were consecutively recruited and compared with one hundred apparently healthy age and sex-matched controls. Blood samples were collected for free thyroxine, free triiodothyronine, thyroid-stimulating hormone and selenium levels. The thyroid hormones were assayed with enzyme-linked immunoassay. Selenium was measured using inductively coupled plasma optical emission spectroscopy. Data were analysed with SPSS Version 26. Results: The mean age of the subjects and control was 40.3 ± 10.6 and 38.0 ± 9.1 years, respectively (p=0.157). The subjects and controls were predominantly females, 80% and 72%, respectively. Thyroid disorders were most prevalent in the 41-50 years age category. The male:female ratio was 1:4. The majority of the cases (60%) had biochemical evidence of hyperthyroidism, 28% were euthyroid and 12% were hypothyroid. Selenium levels were significantly lower among the cases than healthy controls (mean selenium level: 24.9 ± 15.7 and 59.0 ± 35.9 μg/L, respectively, p < 0.001). With normal selenium levels of 80 μg/L, all the participants were deficient in selenium. There was no significant difference in selenium levels across the spectrum of thyroid disorders although the mean selenium levels were lowest for the hypothyroid subjects. Conclusion: There is significant selenium deficiency in all subjects with thyroid disorders; apparently, healthy Nigerians are generally deficient. Selenium supplementation is recommended for Nigerian patients with thyroid disease and may be required for the general population.