Conclusions The effects of testosterone on cardiovascular-related events varied with source of funding .
Nevertheless , overall and particularly in trials not funded by the pharmaceutical industry , exogenous testosterone increased the risk of cardiovascular-related events , with corresponding implication s for the use of testosterone therapy
Background Testosterone therapy is increasingly promoted .
No r and omized placebo-controlled trial has been implemented to assess the effect of testosterone therapy on cardiovascular events , although very high levels of and rogens are thought to promote cardiovascular disease .
Testosterone increases human platelet thromboxane A2 receptor density and aggregation responses.
BACKGROUND The incidence of thrombotic cardiovascular disease is greater in men than in premenopausal women .  Testosterone has been implicated as a significant risk factor for cardiovascular disease and for acute myocardial infa rct ions and strokes in young male athletes who abuse anabolic steroids . Thromboxane A2 ( TXA2 ) is a vasoconstrictor and platelet proaggregatory agent that has been implicated in the pathogenesis of cardiovascular disease . We therefore tested the hypothesis that testosterone regulates the expression of human platelet TXA2 receptors . METHODS AND RESULTS In a double-blind , placebo-controlled , r and omized , parallel-group study , we determined the effects of testosterone cypionate 200 mg IM given twice , 2 weeks apart , or saline placebo in 16 healthy men .  Platelet TXA2 receptor density ( Bmax ) and dissociation constant ( Kd ) were measured by use of the TXA2 mimetic 125I-BOP . Platelet aggregation responses to I-BOP and to thrombin and plasma testosterone concentrations were measured before treatment ( pretreatment phase ) , at 2 and 4 weeks ( active phase ) , and again at 8 weeks ( recovery phase ) . Treatment with testosterone was associated with an increase in the Bmax value from 0.95 + /- 0.13 to 2.10 + /- 0.4 pmol/mg protein ( n = 9 ) , with a peak effect at 4 weeks ( P = .001 ) , returning to baseline by 8 weeks . There was no significant change in Bmax values in the saline-treated group . The Kd values were unchanged . Testosterone treatment was associated with a significant increase in the maximum platelet aggregation response to I-BOP ( P < .001 ) at 4 weeks and returned to baseline at 8 weeks . The EC50 values were not significantly changed . Platelet TXA2 receptor density was positively correlated ( r = .56 , P < .001 , n = 32 measurements ) with pretreatment ( endogenous ) plasma testosterone levels ( range , 215 to 883 ng/dL ) but not Kd . CONCLUSIONS Testosterone regulates the expression of platelet TXA2 receptors in humans . This may contribute to the thrombogenicity of and rogenic steroids
Conclusions The effects of testosterone on cardiovascular-related events varied with source of funding .
Nevertheless , overall and particularly in trials not funded by the pharmaceutical industry , exogenous testosterone increased the risk of cardiovascular-related events , with corresponding implication s for the use of testosterone therapy
Background Testosterone therapy is increasingly promoted .
No r and omized placebo-controlled trial has been implemented to assess the effect of testosterone therapy on cardiovascular events , although very high levels of and rogens are thought to promote cardiovascular disease .