Testosterone vs Mortality

Since I was writing about andropause yesterday, I thought I'd mention a study I stumbled upon (I've got a treasure chest full since I haven't composed anything since the end of July) which ironically was published last month in the UK.  The authors studied 930 men avg 60yo w/CAD who were referred for diagnostic angiography and then followed for ~7yrs. 

When separated into 2 groups dependent upon testosterone (T) levels, those men w/CAD with the lowest T had more than twice the risk of all-cause and vascular mortality compared to those w/CAD & normal T levels.  The only other factors found to impact mortality were left ventricular dysfunction, aspirin use, and beta blocker therapy.

But what constitutes low T?  In this particular study, 20.9% had bio-available T <2.6nmol/L (74.9ng/dL), 16.9% had total T <8.1nmol/L (233ng/dL), and 24% had either.  First, you need to understand that the specific equipment used to measure T will affect the reference range, including the lower limit of normal.  In fact, the reference range for bio-T varies quite dramatically from lab to lab.  However, most facilities use 200-300ng/dL as the lower limit of normal for TT, such that these men most likely would have been considered hypogonadal by most American facilities.  Interestingly, compared to 148 men who were excluded from the study due to normal coronary arteries, those w/CAD had comparable average TT & bio-T. 

It's interesting to note that these mortality findings are consistent w/six others published in the last four years regarding male populations scattered globally, including the VA Puget Sound, Rancho Bernardo, Italy, United Kingdom, Sweden, and National Health and Nutrition Examination Survey (NHANES) III.  Furthermore, this relationship between low T and increased mortality is also found in those men given androgen deprivation therapy to treat their prostate cancers, such that the American Heart Association, American Cancer Society, and American Urological Association published a scientific advisory earlier this year in February detailing their concern.

One final word of caution.  We now know that low T is associated with increased mortality and conversely, normal T is associated with decreased mortality.  However, we haven't yet proven that T supplementation will lower mortality.  So remember, folks, don't try this at home w/o professional supervision!