Men's Health
Testosterone Directory
Testosterone is a hormone that acts as the primary sex hormone in men. It is produced by the male testicles and the female ovaries. Testosterone levels in men increase during and after puberty, dropping again after about age 40. Testosterone causes the deeper voice, bigger muscles, body hair, and other primarily male features. Follow the links below to find WebMD's comprehensive coverage about what testosterone is, what it does in the body, what levels are normal, and much more.
Medical Reference
Features
It’s natural for testosterone levels to decline as men age, but sometimes low testosterone can cause symptoms ranging from low sex drive to depression. This article explains what happens when you have low testosterone and what the options are for treatment.

