Plasminogen activator inhibitor in plasma is related to testosterone in men

Low plasma testosterone and high levels of the rapid inhibitor of plasminogen activator (PA-I) have been proposed as risk factors for myocardial infarction. In this study, the relationship between testosterone and PA-I activity levels in middle-aged men without thrombotic antecedent was investigated. In 54 normogonadic men (testosterone, 7.3 to 29.1 nmol/L), PA-I was related positively to body mass index (BMI) and triglycerides and negatively to testosterone. When these variables were controlled, the relation between PA-I and testosterone remained significant (P less than .01). In the 41 normogonadic men with BMI less than 25, testosterone was the only variable to influence PA-I. Fibrinolytic activity was evaluated by the euglobulin lysis plate method and the specific measurement of functional tissue plasminogen activator. The basal fibrinolytic activity and the response to venous occlusion were essentially controlled by PA-I but were not significantly related to testosterone. In 17 men with severe hypogonadotrophinic hypogonadism (testosterone less than 3 nmol/L), PA-I was significantly increased (18.5 +/- 1.8 AU/mL, mean +/- SE) compared with 9.5 +/- 0.8 AU/mL in 41 normogonadic men of normal weight (P less than .001). However, 14 hypogonadic men had a hypertriglyceridemia or a BMI greater than 25, which could explain high PA-I levels. This study shows that the level of the inhibitor of plasminogen activator is partly dependent on hormonal status in men and provides a link between independently established epidemiologic data.