Causes

The hypothalamus helps keep the body’s internal functions in balance. It helps regulate:

• Appetite and weight
• Body temperature
• Childbirth
• Emotions, behavior, memory
• Growth
• Production of breast milk
• Salt and water balance
• Sex drive
• Sleep-wake cycle and the body clock

Another important function of the hypothalamus is to control the pituitary gland. The pituitary is a small gland at the base of the brain. It lies just below the hypothalamus. The pituitary, in turn, controls the:

• Adrenal glands
• Ovaries
• Testes
• Thyroid gland

There are many causes of hypothalamic dysfunction. The most common are:

• Surgery
• Brain injury
• Brain tumors
• Radiation treatment to the brain

Other causes include:

• Nutrition problems, such as eating disorders (anorexia), extreme weight loss
• Blood vessel problems in the brain, such as aneurysm, pituitary apoplexy, subarachnoid hemorrhage
• Genetic disorders, such as Prader-Willi syndrome, familial diabetes insipidus, Kallmann syndrome
• Infections and swelling (inflammation) due to certain immune system diseases

Symptoms

Symptoms are usually due to the hormones or brain signals that are missing. In children, there may be growth problems, either too much or too little growth. In other children, puberty occurs too early or too late.

Tumor symptoms may include headache or loss of vision.

If the thyroid is affected, there may be symptoms of an underactive thyroid (hypothyroidism). Symptoms may include feeling cold all the time, constipation, fatigue, or weight gain, among others.

If the adrenal glands are affected, there may be symptoms of low adrenal function. Symptoms may include fatigue, weakness, poor appetite, weight loss, and lack of interest in activities.

Hypothalamus Disorders

Sometimes there are problems with your hypothalamus that can cause diseases. These problems can also affect your pituitary gland. Some disorders lead to not enough or too many hormones. Hypothalamus disorders include:‌

Hypothalamic obesity. Injury to the hypothalamus can cause problems with hunger. People who have hypothalamic obesity can have symptoms like:

• Fast weight gain
• Excessive weight gain
• Uncontrollable appetite
• Low metabolism‌

Functional hypothalamic amenorrhea. This condition is sometimes called secondary amenorrhea and happens when you stop having your period.‌

When your body doesn’t have enough energy from food, it can cause you to have high cortisol levels. The cortisol dampens your hypothalamus-ovary connection, which means you’ll have low amounts of hormones. This affects ovulation and leads to absent periods. ‌

Functional hypothalamic amenorrhea can also be caused by a brain tumor. 

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Central diabetes insipidus. This type of diabetes is a rare autoimmune disorder where your immune system damages your hypothalamus. Parts of your hypothalamus release a hormone called antidiuretic hormone, or vasopression, which helps your kidneys filter water and keep you hydrated.  

Damage to the hypothalamus leads to a lack antidiuretic hormone and causes frequent peeing and thirst. ‌

Kallman syndrome. Hypothalamus dysfunction can lead to absent or delayed puberty and no sense of smell, as in Kallman syndrome. This is a genetic condition that causes problems with the hypothalamus. It means you won’t have enough hormones for sexual development. Symptoms can include:

• No periods
• Undescended testicles
• Small penis
• No or small breasts
• Kidney problems
• Hearing problems
• Cleft lip
• Cleft palate‌

Prader-Willi syndrome. This genetic condition is caused by a hypothalamus that doesn’t work properly. This can cause:

• Intellectual disabilities
• Poor growth
• Irresistible urge to eat
• Small genitals
• Obesity
• Behavioral problems‌

Syndrome of inappropriate antidiuretic hormone. SIADH causes high antidiuretic hormone levels and low electrolytes. It’s usually caused by stroke, infection, or cancer that damages the hypothalamus. Too much of this hormone can cause low sodium levels and lead to:

• Weakness
• Throwing up
• Tiredness
• Headaches
• Trouble thinking

Exams and Tests

The health care provider will perform a physical examination and ask about your symptoms.

Blood or urine tests may be ordered to determine levels of hormones such as:

• Cortisol
• Estrogen
• Growth hormone
• Pituitary hormones
• Prolactin
• Testosterone
• Thyroid
• Sodium
• Blood and urine osmolality

Other possible tests include:

• Hormone injections followed by timed blood samples 
• MRI or CT scans of the brain
• Visual field eye exam (if there is a tumor)

Treatment

Treatment depends on the cause of the hypothalamic dysfunction:

• For tumors, surgery or radiation may be needed.
• For hormonal deficiencies, missing hormones need to be replaced by taking medicine. This is effective for pituitary problems and for salt and water balance.
• Medicines are usually not effective for changes in temperature or sleep regulation.
• Some medicines may help with problems related to appetite regulation and weight gain.

Prognosis

Many causes of hypothalamic dysfunction are treatable or reversible. Most of the time, missing hormones can be replaced.