Hypogonadism is the absence of testosterone production by the gonads — the testicles in men and the ovaries in women.
These sex organs produce the hormones testosterone and estrogen, which ultimately determine the differences between men and women.
The two basic types of male hypogonadism are:
Primary causes
This type of hypogonadism — also known as primary testicular failure — originates from an abnormality in the testicles.
Secondary This type of hypogonadism indicates a defect in the brain or in the pituitary gland that's connected to the brain and that controls hormone production. If chemical messages from the pituitary gland to the testicles aren't sent, impaired testicular function occurs. Male hypogonadism can have many causes. Certain diseases and other malfunctions of the testicles or pituitary gland can cause testosterone deficiency.
Hypogonadism Causes
Klinefelter's syndrome This condition results from a congenital abnormality of the sex chromosomes, X and Y. A male normally has only one X and one Y chromosome. In Klinefelter's syndrome, two or more X chromosomes are present in addition to one Y chromosome. The Y chromosome contains the genetic material that determines the sex of a child and related development. The extra X chromosome that occurs in Klinefelter's syndrome causes abnormal development of the testicles. This condition is present in about 1 in 800 live male births.
Undescended testicles Before birth, the testicles develop inside the male infant's abdomen and normally move down into their permanent place in the scrotum 2 months before birth. One or both of the testicles may not be descended at birth. This condition often corrects itself within the first few years of life without treatment. If not corrected in early childhood, it may lead to malfunction of the testicles. A boy born with an undescended testicle has a higher risk of infertility and testicular cancer.
Mumps orchitis If a mumps infection involving the testicles in addition to the salivary glands (mumps orchitis) occurs during adolescence or adulthood, long-term testicular damage may occur. This may affect normal testicular function.
Hemochromatosis Too much iron in the blood can cause testicular failure or pituitary gland dysfunction.
Injury to the testicles Because of their location outside the abdomen, the testicles are prone to injury. Damage to normally developed testicles can cause hypogonadism. Damage to one testicle may not impair testosterone production.
Prior hernia surgery The vascular supply to the testicles can be damaged during hernia repair surgery. Additional surgery may often correct this problem, restoring testosterone and sperm production.
Cancer treatment Chemotherapy or radiation therapy for the treatment of cancer can interfere with testosterone and sperm production. The effects of both treatments often are temporary, but permanent infertility may occur. Although many men regain their fertility within a few months after treatment ends, preserving sperm before starting cancer therapy is an option that many men consider.
Normal aging Older men generally have lower testosterone levels than younger men do. After age 30, there's a slow and continuous decrease in testosterone production. The rate that testosterone declines varies greatly among individual men. About 15 percent to 30 percent of older men have a testosterone level that's below normal.
