Testosterone in men declines with age and ill health, so low testosterone levels tend to correlate with cardiovascular disease risk factors, cardiovascular disease, and mortality. Testosterone replacement is increasingly promoted to older men, although the safety of testosterone replacement has never been assessed in a large trial. Meta-analyses of small, randomized-controlled trials suggest testosterone administration lowers HDL-cholesterol and increases the risk of cardiovascular-related events.
To clarify the role of testosterone without any potentially harmful interventions, a team of researchers from the CUNY School of Public Health, including Prof. Mary C. Schooling, and the University of Hong Kong, recently compared cardiovascular disease risk factors among men by genetically determined levels of testosterone, using an innovative study design—a separate-sample Mendelian randomization study. This study did not corroborate any observed protective effects of testosterone on cardiovascular disease risk factors or risk of cardiovascular disease. Instead, the research confirmed that testosterone lowers HDL-cholesterol and suggested that testosterone raises LDL-cholesterol. Testosterone replacement should be used cautiously, considering the potential detrimental effect on LDL—as well as on HDL—cholesterol, and hence, most likely, increased risk of cardiovascular disease.
Findings are published online in the International Journal of Epidemiology.