Before the ready availability of non-injectible testosterone preparations, and because of their ease of administration by the oral route, 17-alkylated steroids were popular surrogate agents for testosterone. These substances, however, were capable of inducing several risk factors for coronary artery disease (Kopera 1993; Hall and Hall 2005) and as a consequence, particularly after the revelations of extensive 17-alkylated anabolic steroid abuse by athletes, testosterone, became unjustly incriminated. The evidence, however, tends to suggest just the opposite; testosterone may even be cardioprotective. Dunajska and colleagues have demonstrated that when compared to controls, men with coronary artery disease tend to have: lower total testosterone levels and free androgen indices, more abdominal fat, higher blood sugar and insulin levels (Dunajska et al 2004).
Testosterone makes a contribution to nitric oxide formation. Nitric oxide, released from penile nerves stimulates guanylate cyclase which catalyzes the transformation of guanosine-5-triphosphate into 3′,5′-cyclic, guanosine monophosphate (cyclic GMP). Gyclic GMP causes vasodilatation and hence erection formation (Morelli et al 2005). The breakdown of cyclic GMP to GMP is mediated by the enzyme, phosphodiesterase type-5, the inhibitors of which (eg, sildenafil citrate) enhance erection formation and maintanence (Carson and Lue 2005).
Total levels of testosterone in the body are 264 to 916 ng/dL in men age 19 to 39 years,[165] while mean testosterone levels in adult men have been reported as 630 ng/dL.[166] Levels of testosterone in men decline with age.[165] In women, mean levels of total testosterone have been reported to be 32.6 ng/dL.[167][168] In women with hyperandrogenism, mean levels of total testosterone have been reported to be 62.1 ng/dL.[167][168]
Saw palmetto: Uses, dosage, and side effects Saw palmetto is an extract from the berries of a type of palm tree. The berries have traditionally been used to ease urinary and reproductive problems. The extract is now used in herbal remedies to stabilize testosterone. Learn about its use, its effectiveness, the science behind the claims, and any side effects. Read now