Association Between Non-Scarring Alopecia and Hypothyroidism: A Bidirectional Two-Sample Mendelian Randomization Study

The Mendelian randomization study used data from genome-wide association studies involving 361,822 participants for alopecia areata (AA), 201,214 participants for androgenetic alopecia (AGA), and 462,933 participants for hypothyroidism. The study found a bidirectional causal relationship between AA and hypothyroidism, but no such relationship was found between AGA and hypothyroidism. This suggests that each condition, AA and hypothyroidism, increases the risk of the other. The study recommends that physicians should include thyroid function tests in the clinical assessment of AA patients and be aware that patients with hypothyroidism are at an increased risk of developing AA. The study's limitations include the inability to analyze the effects of other variables, such as age, race, and sex.