Testosterone supplementation did not show consistent benefit for cardiovascular risk , sexual function , mood and behavior , or cognition .
Studies that examined clinical cardiovascular endpoints have not favored testosterone therapy over placebo .
Testosterone is ineffective in treating erectile dysfunction and controlled trials did not show a consistent effect on libido .
Testosterone supplementation consistently increased muscle strength but did not have beneficial effects on physical function .
Most studies on mood-related endpoints found no beneficial effect of testosterone treatment on personality , psychological well-being , or mood .
Testosterone products are recommended by some prescribers in response to a diagnosis or presumption of " low testosterone " ( low-T ) for cardiovascular health , sexual function , muscle weakness or wasting , mood and behavior , and cognition .
Testosterone treatment and mortality in men with low testosterone levels.
CONTEXT Low testosterone levels in men have been associated with increased mortality . However , the influence of testosterone treatment on mortality in men with low testosterone levels is not known . OBJECTIVE The objective of the study was to examine the association between testosterone treatment and mortality in men with low testosterone levels . DESIGN This was an observational study of mortality in testosterone-treated compared with untreated men , assessed with time-varying , adjusted Cox proportional hazards regression models . Effect modification by age , diabetes , and coronary heart disease was tested a priori . SETTING The study was conducted with a clinical data base that included seven Northwest Veterans Affairs medical centers . PATIENTS Patients included a cohort of 1031 male veterans , aged older than 40 yr , with low total testosterone [ ≤250 ng/dl ( 8.7 nmol/liter ) ] and no history of prostate cancer , assessed between January 2001 and December 2002 and followed up through the end of 2005 . MAIN OUTCOME MEASURE Total mortality in testosterone-treated compared with untreated men was measured . RESULTS Testosterone treatment was initiated in 398 men ( 39 % ) during routine clinical care . The mortality in testosterone-treated men was 10.3 % compared with 20.7 % in untreated men ( P<0.0001 ) with a mortality rate of 3.4 deaths per 100 person-years for testosterone-treated men and 5.7 deaths per 100 person-years in men not treated with testosterone . After multivariable adjustment including age , body mass index , testosterone level , medical morbidity , diabetes , and coronary heart disease , testosterone treatment was associated with decreased risk of death ( hazard ratio 0.61 ; 95 % confidence interval 0.42 - 0.88 ; P = 0.008 ) . No significant effect modification was found by age , diabetes , or coronary heart disease . CONCLUSIONS In an observational cohort of men with low testosterone levels  , testosterone treatment was associated with decreased mortality  compared with no testosterone treatment . These results should be interpreted cautiously because residual confounding may still be a source of bias . Large , r and omized clinical trials are needed to better characterize the health effects of testosterone treatment in older men with low testosterone levels
Testosterone supplementation did not show consistent benefit for cardiovascular risk , sexual function , mood and behavior , or cognition .
Studies that examined clinical cardiovascular endpoints have not favored testosterone therapy over placebo .
Testosterone is ineffective in treating erectile dysfunction and controlled trials did not show a consistent effect on libido .
Testosterone supplementation consistently increased muscle strength but did not have beneficial effects on physical function .
Most studies on mood-related endpoints found no beneficial effect of testosterone treatment on personality , psychological well-being , or mood .
Testosterone products are recommended by some prescribers in response to a diagnosis or presumption of " low testosterone " ( low-T ) for cardiovascular health , sexual function , muscle weakness or wasting , mood and behavior , and cognition .