Hormonal, biochemical parameters and blood microelement levels in young women with subclinical hypothyroidism combined with thyroid peroxidase antibody positivity
Authors:   Karaganda Medical University, Serikbayeva A.A. ,   Karaganda, Kazakhstan, Rymar O.D. ,   Research Institute of Internal and Preventive Medicine – Branch of the Institute of Cytology and Genetics, Siberian Branch of Russian Academy of Sciences; Novosibirsk, Russian Federation, Shcherbakova L.V. ,   Research Institute of Internal and Preventive Medicine – Branch of the Institute of Cytology and Genetics, Siberian Branch of Russian Academy of Sciences; Novosibirsk, Russian Federation, Tauesheva Z.B. ,   Karaganda Medical University; Karaganda, Kazakhstan
Published: September 2024

Many studies have been devoted to investigating the relationship between subclinical hypothyroidism (SH), thyroid gland (TG) autoimmunity, and blood trace elements; however, the data presented in these studies are often contradictory. Aim of study. To identify the factors associated with SH in combination with the presence of Anti-thyroid peroxidase antibody (TPO-Ab). Design. Single-center, observational, single-cohort, cross-sectional, and uncontrolled study. Materials and Methods. This study analyzed 859 women aged 18–45 with SH and without TG dysfunction. Based on thyroid function and TPO-Ab status (presence (+) or absence (–)), four study groups were formed: Group 1 — Euthyroidism and TPO-Ab(–) (n = 503); Group 2 — Euthyroidism and TPO-Ab(+) (n = 164); Group 3 — SH and TPO-Ab(–) (n = 128); Group 4 — SH and TPO-Ab(+) (n = 64). Determination of thyroid-stimulating hormone (TSH), free thyroxine (FT4), and TPO-Ab levels in serum was provided by enzyme immunoassay on the Evolis Robotized System using the test systems "Thyroid-ELISA-TSH, 0.23–3.4 µIU/ml", "Thyroid-ELISA FT4, 10–23.2 pmol/l", and "Thyroid ELISA-TPO-Ab < 30 U/ml". The reference values were taken from the instructions of the manufacturer Alkor Bio Group (Russia). Measurement of element concentrations was conducted on the atomic absorption spectrometer "МГА-915МД" from Lumex (Russia). Logistic regression analysis with a series of univariate and multivariate models was performed to determine independent predictors of the likelihood of SH and TPO-Ab positive status (relative to euthyroid and TPO-Ab negative individuals). Results. In young women, a decrease in FT4 is associated with increasing age, elevated levels of TSH, TPO-Ab, mercury, decreased heart rate, and reduced levels of thyroglobulin, alkaline phosphatase (ALP), manganese, nickel, selenium, lead, and the triglyceride/glucose index. An increase in TSH is associated with lower levels of ALP, manganese, and nickel, and higher mercury levels. The likelihood of having SH combined with the presence of TPO-Ab, compared to the group without thyroid dysfunction and elevated antibodies, increases with reduced concentrations of iodine (odds ratio (OR) = 0.739; 95% confidence interval (CI): 0.618–0.884, p = 0.001), selenium (OR = 0.987; 95% CI: 0.976–0.998, p = 0.018), and zinc (OR = 0.998; 95% CI: 0.997–0.999, p = 0.023), and with elevated lead levels (OR = 1.106; 95% CI: 1.006–1.217, p = 0.038). In a multivariate regression model, the probability also increases with decreased iodine and cadmium levels, and elevated lead levels. Conclusion. Reduced concentrations of iodine, selenium, and zinc, along with elevated blood lead levels, are factors associated with the activation of thyroid autoimmunity and the presence of SH in combination with elevated TPO-Ab levels. Keywords: thyroid gland, thyroid function hormones, microelements, thyroid peroxidase antibodies, young age, women.