Correlation of thyroid hormones with levels of iron and selenium in women with hypothyroidism in Basrah, Iraq

Abstract

Introduction and aim. Trace elements play a critical role in thyroid hormone synthesis and metabolism; however, data on their combined alterations in hypothyroid women from the Middle East remain limited. This study aimed to evaluate the relationship between serum selenium (Se) and iron (Fe) levels and thyroid function in women with overt and subclinical hypothyroidism compared with euthyroid controls. Material and methods. In this case-control study, 312 women were enrolled, including 194 patients with hypothyroidism and 118 age- and body mass index-matched euthyroid controls recruited in Basra, Iraq. Serum thyroid-stimulating hormone (TSH), free thyroxine (FT4), iron (Fe), and Se were measured using standardized automated assays. Results. Hypothyroid women had significantly higher median thyroid-stimulating hormone levels than controls (4.51 [1.9–7.5] vs. 1.45 [0.98–2.1] mU/L; p<0.0001) and lower median free thyroxine concentrations (12.48 [9.0–16.47] vs. 16.73 [14.16–20.59] pmol/L; p<0.0001). Serum iron levels were significantly reduced in hypothyroid patients (11.52 [7.79–15.83] vs. 15.90 [10.47–19.42] µmol/L; p<0.0001), as were selenium levels (0.81 [0.55–1.12] vs. 1.45 [1.18–1.92] µmol/L; p<0.0001). Age correlated positively with thyroid-stimulating hormone (Spearman’s ρ=0.449, p<0.001) and negatively with free thyroxine (ρ=-0.301, p=0.007), while no significant correlations were observed for iron or selenium. Conclusion. Women with hypothyroidism exhibited combined selenium and iron deficiencies alongside marked hormonal disturbances. To our knowledge, this is one of the first large case-control studies in women from southern Iraq to simultaneously assess selenium and iron status in relation to thyroid function. These findings support the potential clinical relevance of routine micronutrient assessment in hypothyroid patients, particularly in regions with known dietary deficiencies.