Effects of Lifelong Testosterone Exposure on Health and Disease Using Mendelian Randomization

The 2020 study "Effects of lifelong testosterone exposure on health and disease using Mendelian randomization" used data from the UK Biobank and Mendelian randomization to investigate the impact of testosterone on health and disease in over 500,000 participants. The researchers found that higher testosterone levels were associated with an increased risk of type 2 diabetes in women, prostate cancer in men, and polycystic ovary syndrome in women, but could protect against autoimmune diseases and alopecia in both genders. In men, increased testosterone was linked to increased bone mineral density, decreased body fat, and increased risks of prostate cancer, androgenic alopecia, spinal stenosis, and hypertension. The study also found that each 0.1 nmol/L increase in calculated free testosterone (CFT) was associated with increased risks of prostate cancer, androgenic alopecia, and hematocrit percentage, but beneficial effects on increased heel bone mineral density, increased body fat-free percentage, and decreased body fat percentage. The researchers concluded that the benefits of long-term increased testosterone should be considered against its adverse effects, notably increased prostate cancer and hypertension, and suggested that well-powered randomized trials are needed to conclusively address the risks and benefits of testosterone treatment.