ABSTRACT
PURPOSE: To identify a possible relation between erectile capacity and serum testosterone concentrations in men with normal testicles and erectile dysfunction. PATIENTS AND METHODS: We studied 206 patients with erectile dysfunction who had no anatomic defect in their sex organs and no vascular risk factors or history of operation or trauma. The protocol included assay of serum testosterone in the morning and duplex ultrasonography after pharmacologic induction of erection using prostaglandin E1. The subjects were assigned to three groups according to their serum testosterone concentration: low (700 ng/dL). Some clinical factors, the result of duplex flow study, and pharmacologic erection test findings were compared. RESULTS: The residual spontaneous erectile rigidity of the three groups was 43.5% in the low, 46.5% in the normal, and 37.6% in the high group (p>0.05). The mean penile rigidities after injection of PGE1 in the low, normal, and high testosterone groups were 73.8%, 78.1%, and 81.9%, respectively (p>0.05). The differences in peak systolic velocity (PSV), end-diastolic velocity (EDV), and resistance index (RI), which are indicators of penile hemodynamics, did not reach statistical significance between these groups. However, the average age of the low-testosterone group was significantly greater than the averages of the other two groups (p<0.05). CONCLUSIONS: There was no significant relation between serum testosterone concentration and erectile capacity in patients with erectile dysfunction who had normal testicles. Our data imply a serum testosterone threshold for penile erection which is much lower than the normal laboratory range.