The Relationship and Mechanisms Between Body Mass Index and Autoimmune Hypothyroidism: Insights from Mendelian Randomization.

BACKGROUND

Obesity is increasingly prevalent worldwide and has been linked to various health conditions, including hypothyroidism.

METHODS

Summary-level GWAS data from the UK Biobank and the FinnGen Biobank were used for Mendelian randomization analysis. The impact of BMI on autoimmune hypothyroidism through putative mediators was assessed through a four-step analytical process. Statistical analyses, including the inverse-variance-weighted (IVW) method, weighted median (WM), and MR-Egger methods, were employed to evaluate causal relationships and detect horizontal pleiotropy. Mediation analysis was performed using a two-step method to assess the causal relationships between BMI, putative mediators, and autoimmune hypothyroidism.

RESULTS

Higher BMI was associated with an increased risk of autoimmune hypothyroidism. Mean corpuscular volume, eosinophil count, and cystatin C levels were found to mediate this association.

CONCLUSIONS

BMI positively correlates with autoimmune hypothyroidism, with mean corpuscular volume, eosinophil count, and cystatin C levels mediating this relationship. Further research is needed to confirm these findings and explore causal relationships across diverse populations.