Hypothalamic dysfunction involves the region of the brain called the hypothalamus. This area is located behind the eyes and helps control the pituitary gland, particularly in response to stress. The pituitary in turn controls the thyroid, adrenal glands, ovaries, and testes.

The hypothalamus also helps regulate weight and appetite, body temperature, salt and water balance, and emotions. It is also involved in growth, milk production, childbirth, and sleep.

Causes of hypothalamic dysfunction include tumors (growths), surgery, radiation, infections and inflammation, genetic disorders, head trauma, bleeding, malnutrition, and excess iron. The most common tumors in the area are craniopharyngiomas in children.

Anorexia (excessive voluntary weight loss) and bulimia (vomiting induced to reduce weight) can also cause hypothalamic dysfunction.

If a tumor is present, there may be headaches or loss of vision. Symptoms generally relate to the hormones that are missing. In children, there may be growth problems -- either too much growth or too little -- or puberty that occurs too early or too late.

Hypothyroidism may occur, causing fatigue, cold intolerance, weight gain, and hair or skin changes. Menstrual disturbance, impotence, breast enlargement, and loss of body hair and muscle (in men) may occur. Low adrenal function may cause dizziness and weakness. Less commonly, patients may also experience obesity, body temperature disturbance, emotional abnormalities, excessive thirst, or uncontrolled urination.

A variant of hypothalamic dysfunction that occurs in men, called Kallmann's syndrome, includes hypogonadism (lowered function of sexual hormones) and an inability to smell.

Blood or urine tests will be done to determine levels of hormones such as thyroid, prolactin, cortisol, estrogen, testosterone, and growth hormone. Pituitary hormones will be checked and are usually easier to measure than are hypothalamic hormones.

Specialized tests may be needed, including hormone injections followed by timed blood samples. If a tumor is present, an eye test called a visual field exam may be done. MRI or CT scans may be done to image the brain.

Treatment depends on the cause of the hypothalamic dysfunction. Surgery or radiation may be needed to treat tumors. Specific treatment for bleeding infection and other causes may be available. Hormonal deficiencies are treated by replacing the missing hormones.

Many causes of hypothalamic dysfunction are treatable and most of the time hormone deficiencies can be replaced.

Complications of hypothalamic dysfunction depend on the cause. Complications of brain tumors include permanent blindness or vision disorders and specific dysfunctions related to the brain area where the tumor occurs. Hypothyroidism may increase cholesterol and the risk of heart problems. Adrenal insufficiency may lead to an inability to deal with stress (such as surgery or infection).

Gonadal deficiency may lead to infertility, increased risk for heart disease and osteoporosis (thin bones) in women; and impotence, infertility and osteoporosis in men. Growth hormone deficiency can cause weakness, increased cholesterol and osteoporosis as well. In children, growth hormone deficiency causes short stature.

Call your doctor if you note headaches, visual problems, or any of the symptoms of hormonal deficiency or excess.

It is important to maintain a healthy diet and not exercise too strenuously or lose weight too rapidly. If you believe you have an eating disorder such as anorexia or bulimia, seek medical attention: these conditions can be life-threatening.

People with evidence of hormonal deficiencies should discuss replacement therapy with their doctors.