This study claims that maintaining T levels above 550ng actually reduced cardiac disease risk. Note that they tested estradiol levels, which was lacking in the inaccurate study recently published. In addition, they found positive correlation between T levels are type 2 diabetes risk. This study was done over 5 years and analyzed all kinds of markers, including SHBG.
The implications of low testosterone on mortality in men Testosterone levels in men slowly decline with aging and also decline more abruptly due to medical illness or medications. Prescriptions for testosterone have increased dramatically over the past decade, since a testosterone-gel formulation was approved and since numerous studies reported an association between low serum testosterone and increased mortality. However, recent observational studies of testosterone treatment have reported conflicting results with some studies reporting decreased risks for mortality while others reported increased mortality risks with testosterone treatment. This paper will summarize recent studies of low serum testosterone and mortality and testosterone treatment and mortality and what the potential implications of these studies are for the clinician.
The Journal of Clinical Endocrinology & Metabolism 2008 Jan;93(1):68-75.
Low Serum Testosterone and Mortality in Older Men.
Gail A. Laughlin, Eliza beth Barrett-Connor and Jaclyn Bergstrom. Department of Family and Preventive Medicine, School of Medicine, University of California, San Diego, La Jolla, California 92093
Results: During an average 11.8-yr follow-up, 538 deaths occurred. Men whose total testosterone levels were in the lowest quartile (<241 ng/dl) were 40% more likely to die than those with higher levels, independent of age, adiposity, and lifestyle. Additional adjustment for health status markers, lipids, lipoproteins, blood pressure, glycemia, adipocytokines, and estradiol levels had minimal effect on results. The low testosterone-mortality association was also independent of the metabolic syndrome, diabetes, and prevalent cardiovascular disease but was attenuated by adjustment for IL-6 and C-reactive protein. In cause-specific analyses, low testosterone predicted an increased risk of cardiovascular and respiratory disease (HR mortality but was not significantly related to cancer death. Results were similar for bioavailable testosterone.
Conclusions: Testosterone insufficiency in older men is associated with increased risk of death over the following 20 yr, independent of multiple risk factors and several preexisting health conditions.