Relationship of Hypothyroidism with Alopecia Areata and Androgenetic Alopecia: Insights from a Two-Sample Mendelian Randomization Study

This study used a two-sample Mendelian Randomization (MR) approach to investigate the causal relationship between hypothyroidism and alopecia areata (AA) and androgenetic alopecia (AGA) using data from over 500,000 Finnish biobank samples. The MR analysis found a significant causal relationship between hypothyroidism and an increased risk of AA (OR, 1.34; CI, 1.16–1.56; P = 0.0001), but no significant association with AGA. Sensitivity analyses confirmed the robustness of these findings. The study highlights the importance of thyroid function assessments in patients with AA and suggests that hypothyroidism may contribute to AA development. However, no effective SNPs were identified for AA and AGA using stringent Bonferroni correction, and the findings are based on patients of European descent, which may limit generalizability. Future high-quality randomized controlled trials are recommended to further validate these associations.