• Trace element status and hypothyroidism: A systematic review and meta-analysis
  • Sepide Talebi ,1,* Gholamreza Askari ,2 Hamed Mohammadi ,3
    1. Student Research Committee, Department of Community Nutrition, School of Nutrition and Food Science, Isfahan University of Medical Sciences, Isfahan, Iran
    2. Food Security Research Center and Department of Community Nutrition, School of Nutrition and Food Science, Isfahan University of Medical Sciences, Isfahan, Iran
    3. Student Research Committee, Department of Clinical Nutrition, School of Nutrition and Food Science, Isfahan University of Medical Sciences, Isfahan, Iran


  • Introduction: The metabolism of thyroid hormones has been linked with alterations in trace element levels. However, previous reports comparing trace element levels in hypothyroid patients and healthy individuals had yielded equsivocal results. Therefore, the aim of this meta-analysis was to investigate the association between trace element (selenium (Se), zinc (Zn), iron (Fe) and copper (Cu)) concentrations in hypothyroid patients and healthy subjects.
  • Methods: Electronic databases including PubMed, Scopus, Embase, and Web of Science were searched systematically until October 2018. Eighteen observational studies were included. Hedges’ g was used as the effect sizes, due to trace element levels were presented in different units among studies.
  • Results: Our results revealed that lower Se concentration in patients with hypothyroidism compared with controls (Hedges’ g= −0.45; 95% CI = [−0.88, -0.02]; P = 0.042), whereas no change in copper between two groups (Hedges’ g= −0.09; 95% CI = [−0.40, 0.23]; P = 0.586). In the subgroup analysis based on disease severity, Zn level was found to be lower in overt hypothyroid patients (Hedges’ g= −1.19; 95% CI = [−2.33, -0.04]; P = 0.04), while Fe (Hedges’ g= −1.11; 95% CI = [-2.21, -0.02]; P = 0.046) and Se (Hedges’ g= −0.51; 95% CI = [-0.86, -0.16]; P = 0.004) level were significantly lower in subclinical hypothyroidism.
  • Conclusion: Present meta-analysis found lower Se concentration in patients with hypothyroidism, whereas no significant differences in Cu between two groups. In addition, we found decreased concentration of Zn in overt hypothyroid patients and decreased Fe and Se level in subclinical hypothyroidism. Further studies with higher quality and large sample size are required to determine more exact link between trace element and hypothyroidism.
  • Keywords: Trace elements, Hypothyroidism, Meta-analysis