The cause of hypogonadism may be "primary" or "central." In primary hypogonadism, the ovaries or testes themselves do not function properly. Some causes include surgery; radiation; genetic and developmental disorders; liver and kidney disease; infection; and certain auto-immune disorders. The most common genetic disorders are Turner syndrome (in women) and Klinefelter syndrome (in men).

In central hypogonadism, the centers in the brain that control the gonads (hypothalamus and pituitary) do not function properly. Some causes of central hypogonadism include tumors (growths); surgery and radiation; infections; trauma; bleeding; genetic problems; nutritional deficiencies; and iron excess (hemochromatosis).

A genetic cause of central hypogonadism which also produces an inability to smell is Kallmann syndrome (males). The most common tumors affecting the pituitary area are craniopharyngioma (children) and prolactinoma (adults, this leads to the production of excess prolactin (which causes the breasts to produce milk, among other functions). Prolactinomas cause hypogonadism even if they are not large.

In girls, hypogonadism during childhood will result in lack of menstruation and breast development and short height. If hypogonadism occurs after puberty, symptoms include loss of menstruation, low libido, hot flashes, and loss of body hair.

In boys, hypogonadism in childhood results in lack of muscle and beard development and growth problems. In men the usual complaints are sexual dysfunction, decreased beard and body hair, breast enlargement, and muscle loss.

If a brain tumor is present (central hypogonadism) there may be headaches or visual loss, or symptoms of other hormonal deficiencies (such as hypothyroidism). In the case of the most common pituitary tumor, prolactinoma, there may be a milky breast discharge. People with anorexia nervosa (excessive dieting to the point of starvation) also may have central hypogonadism.

Tests may be done that check estrogen level (women) and testosterone level (men) as well as FSH level and LH level, the pituitary hormones that stimulate the gonads. Other tests may include a thyroid level; sperm count; prolactin level (milk hormone); blood tests for anemia, chemistries, and iron; and genetic analysis.

Sometimes imaging is necessary, such as a sonogram of the ovaries. If pituitary disease is suspected, an MRI or CT scan of the brain may be done.

Hormonal preparations are available for men and women. Estrogen comes as a patch or pills. Testosterone can be given as a patch or via injection.

For women who have not had their uterus removed, combination treatment with estrogen and progesterone is often recommended to decrease the chances of developing endometrial cancer. In addition, low dose testosterone can be added for hypogonadal women with a low sex drive.

If there is a correctible cause of hypogonadism (e.g., a pituitary tumor), medication may be given (particularly for prolactinoma) or surgery and/or radiation therapy may be required. Injections or oral medication can be used to stimulate ovulation. Injections of pituitary hormones may be needed for men with hypogonadism to produce sperm. Therapy may also target nutritional, infectious, or other causes of the problem.

Many forms of hypogonadism are potentially treatable and have a good prognosis.

In women, hypogonadism may cause infertility. Menopause is a form of naturally occurring hypogonadism, which can cause hot flashes, vaginal dryness, and irritability as a woman's estrogen levels fall. The risk of osteoporosis and heart disease increase after menopause.

Some women opt to take estrogen therapy, particularly women who have early menopause ("premature ovarian failure"). However, there is a small but significant increase in risk for breast cancer and heart disease with use of hormone replacement for treatment of menopause.

In men, hypogonadism results in loss of sex drive and may cause weakness, impotence, infertility, and osteoporosis. Men also experience some decline in testosterone as they age, but it is not as dramatic or steep as the decline in sex hormones experienced by women.

Consult with your doctor if you notice loss of menstruation, breast discharge, inability to conceive, hot flashes (women), impotence, loss of body hair, weakness, or breast enlargement (men). Both men and women should call their health care providers if headaches or visual problems occur.

Maintain normal body weight and healthy eating habits to prevent anorexia nervosa. Other causes may not be preventable.