Circulating sex steroids do not influence risk of thyroid malignancy: insights from a bidirectional Mendelian randomization

This study provides genetic evidence that circulating sex steroids are not causally related to thyroid malignancy risk. The weak association between thyroid malignancy and SHBG levels appears largely mediated by the combined influence of testosterone, estradiol, and TSH, reflecting shared hormonal regulation. These findings suggest that natural variation in sex hormone levels has little impact on thyroid cancer susceptibility, and the minor SHBG elevation associated with thyroid malignancy requires further clarification.