In men, testosterone is the main hormone that is responsible for sperm production and sexual function. Hypogonadism results when testosterone levels are below normal. Typical symptoms include a low sex drive, erectile dysfunction, infertility, fatigue, weight gain and enlarged breasts. Over time, hypogonadism can lead to bone loss, which increases the risk of fractures. There are many causes of hypogonadism in men, including pituitary tumors, testicular tumors, history of undescended testes, medications, surgery, radiation and infection. Hypogonadism can also be a part of the natural aging process.
Hypogonadism can be diagnosed in men through blood tests. Additional testing can include a bone density test to evaluate for bone loss. Treatment usually involves testosterone replacement, which can be given in the form of gels, patches or injections. Because there are risks associated with long-term testosterone use, treatment should only be prescribed after a thorough evaluation, including a discussion of the risks and benefits.