Some 5 million men have low levels of the hormone testosterone, according to the National Institutes of Health, or NIH. Testosterone is necessary for muscle and bone strength, sperm production and sex drive. It also helps regulate fat distribution and the production of red blood cells. Testosterone may even improve mood, memory and energy levels.
Starting around age 30, testosterone levels gradually decline at a rate of about 1 percent per year, notes MayoClinic.com. Certain diseases and medications can also contribute to low testosterone levels in men.
Genetic and Congenital Disorders
Certain genetic conditions can cause testosterone levels to plummet, according to the University of Pittsburgh Medical Center, or UPMC. They include myotonic dystrophy, which causes testicular failure in men in their 30s.
Some congenital disorders, which are present at birth but not necessarily inherited, may also lead to abnormally low testosterone levels. Kallman's syndrome, for example, prevents the testicles from developing during adolescence.
Diseases of the Pituitary Gland, Hypothalamus and Testes
Conditions and diseases that afflict the pituitary gland, hypothalamus and testes may all cause testosterone levels to decline in men, according to the UPMC. The hypothalamus is an area of the brain that controls hormone secretion, which affects the operation of the pituitary, or 'master,' gland.
Damaged testicular cells can also cause a decline in testosterone levels. Inflammation of the testes, testicular cancer, injury and accidents can all these harm cells.
Additional Disease and Conditions
Alcoholism, cirrhosis of the liver and chronic kidney failure can all reduce testosterone levels in adult men, according to the Cleveland Clinic. Other conditions such as hemochromatosis, which causes excess amounts of iron in the body, and sarcoidosis, which causes lungs and other organs to become inflamed, may also prompt the amount of testosterone to plummet.
Medical Treatments and Drugs
Chemotherapy and radiation treatments can affect testosterone levels in adult men, as can some medications, according to the UPMC. Medications including morphine, steroids and hormone analogues used to treat prostate cancer may all cause testosterone levels to fall off.
Testosterone therapy may benefit men with abnormally low levels of the hormone, according to Harvard Health Publications. It remains uncertain whether additional testosterone can enhance the health or well-being of men with normal or near-normal levels.
