Cavernous and systemic testosterone plasma levels during different penile conditions in healthy males and patients with erectile dysfunction

Objectives. To determine the testosterone plasma levels in the cavernous an d peripheral blood taken during different penile conditions from patients w ith erectile dysfunction (ED) and to evaluate whether these courses are dif ferent from those detected in the blood of healthy males. Although the dete rmination of the systemic testosterone concentration (TC) has been fairly w ell established in the diagnostic workup of ED, the exact role of testoster one in adult male sexual function remains unclear. Methods. Blood samples were drawn simultaneously from the corpus cavernosum and cubital vein of 54 healthy males with normal erectile function and 46 patients with ED during the penile stages of flaccidity, tumescence, rigidi ty (reached by the healthy males only), and detumescence. Tumescence and ri gidity were induced by audiovisual and tactile stimulation. The TC was dete rmined by means of a radioimmunoassay. Results. In the flaccid phase, the TC in the cavernous blood taken from the healthy volunteers was 2.9 +/- 1.2 ng/mL. The TC significantly increased d uring tumescence (4.3 +/- 1.3 ng/mL) and rigidity (4.4 +/- 1.4 ng/mL), P <0 .001. In the detumescence phase, the TC decreased appreciably to 3.5 +/- 1. 4 ng/mL. In the systemic blood, the increase from flaccidity (4.1 +/- 1.1 n g/mL) to tumescence (4.4 +/- 1.4 ng/mL) was found to be less pronounced but , nevertheless, significant (P = 0.001). No further increase was detected d uring rigidity. From rigidity to detumescence, the systemic TC dropped to 4 .1 +/- 1.2 ng/mL. In the patients with ED, the mean increase in systemic an d cavernous testosterone levels from flaccidity (cubital vein 3.0 +/- 1.0 n g/mL, corpus cavernosum 2.6 +/- 1.0 ng/mL) to tumescence (cubital vein 3.2 +/- 1.1 ng/mL, corpus cavernosum 3.0 +/- 1.0 ng/mL) was less pronounced. Ne vertheless, the course of testosterone detected in the systemic and caverno us plasma of the patients during flaccidity, tumescence, and detumescence r esembled that registered in the healthy controls. In the flaccid phase, the mean cavernous TC in the healthy subjects was found to be 30% lower than t he level in the peripheral blood; in the patients with ED, this difference was only 13%. Conclusions. In the healthy males, the penile erection was accompanied by a n increase in the cavernous and peripheral TC. The difference between the p eripheral and cavernous TC in the healthy subjects and patients with ED in the flaccid phase, when the blood flow through the cavernous body is minimi zed, might be a diagnostic tool to evaluate the amount of bioavailable test osterone, as well as the density of testosterone receptors, in the cavernou s smooth musculature. UROLOGY 58: 435-440, 2001. (C) 2001, Elsevier Science Inc.