Erectile Dysfunction and Testosterone Deficiency

Abstract

A definitive role of testosterone in erectile function has been controversial; however, recent evidence is becoming available which substantiates a key function for this hormone. Testosterone deficiency is associated with a decline in erectile function and testosterone levels are inversely correlated with increasing severity of erectile dysfunction. Erectile dysfunction can be caused by multifactorial pathologies. In particular, erectile dysfunction may be the first symptom of cardiovascular disease. Animal studies have demonstrated that castration causes vascular smooth muscle cell atrophy, venous leakage, adipocytes in the subtunical space, loss of elastic fibers and increase in collagen deposition. Testosterone increases the expression of nitric oxide synthase and phosphodiesterase type 5, both principal enzymes involved in the erectile process. Testosterone replacement alone in hypogonadal men can restore erectile function. A significant proportion of men who fail to respond to a PDE5 inhibitor are testosterone deficient. Testosterone replacement therapy can convert over half of these men into phosphodiesterase type 5 responders. It is now recommended that testosterone levels should be assessed in all patients with erectile dysfunction.

The Princeton III Consensus Recommendations for the Management of Erectile Dysfunction and Cardiovascular Disease

“…46 Buvat and Bou Jaoude, 47 in a compilation of data from 7000 men with ED in 9 large series, reported serum testosterone levels less than 300 ng/dL (to convert to nmol/L, multiply by 0.0347) in 12%, including 4% before and 15% after age 50 years. Hypogonadism is a potential cause of lack of response to PDE5 inhibitor therapy, 48,49 and TRT improves response. 49 This finding suggests that a minimal level of testosterone is required for a complete effect of PDE5 inhibitor therapy.…”

Erectile dysfunction – overview from a cardiovascular perspective

“…Of note, testing of testosterone levels is particularly recommended in patients with failed PDE-5 inhibitor treatment [24]. Testosterone levels < 200 ng/dl are considered low and supplementation may be considered [25].…”

“…However, these medications are not recommended by the German (DGU: Deutsche Urologie Gesellschaft) and the American Urological Association (AUA). Testosterone supplementation is controversial but may be considered in patients with low testosterone levels presenting concomitantly with abnormal nocturnal erections [25,27].…”

New treatments for erectile dysfunction

“…It is now recommended that testosterone levels should be assessed in all patients with ED. 22 Regenerative therapies Current treatments for ED in patients with diabetes are limited in their application towards the attainment of symptomatic relief rather than reversing the underlying vasculogenic and neurogenic aetiologies. Accordingly, regenerative therapies are geared towards regenerating damaged erectile tissue and restoring erectile function using disease-modifying approaches based upon stem cells and tissue engineering, growth factor therapy, and gene transfer.…”