Diabetes insipidus - central

Alternative names
Central diabetes insipidus

Definition
Central diabetes insipidus is a rare condition - marked by extreme thirst and excessive urine output - caused by a deficiency of the hormone vasopressin that normally would limit the amount of urine made. See also diabetes insipidus - nephrogenic.

Causes, incidence, and risk factors

Central diabetes insipidus is a rare condition caused by damage to the hypothalamus or pituitary gland in the brain. Damage may be related to surgery, infection, inflammation, tumor, or injury to the head. Sometimes the cause remains unknown. Very rarely, diabetes insipidus can be caused by a genetic defect.

Normally, the hypothalamus in the brain makes vasopressin, a hormone that causes the kidneys to conserve water by making concentrated urine. In diabetes insipidus, there is a lack of vasopressin. Without vasopressin, the kidneys fail to reabsorb excess filtered water. This results in a rapid loss of water from the body in the form of dilute urine.

A person with diabetes insipidus drinks large quantities of water, driven by extreme thirst, to compensate for the water loss.

Symptoms

     
  • Increased urine volume  
  • Excessive thirst  
  • Confusion and changes in consciousness if the patient is unable to drink

Signs and tests

     
  • Urinalysis  
  • Low urine salt concentration  
  • Urine output greater than 3 liters a day  
  • Water restriction test: while the patient is hospitalized - urine volume and ability of the kidney to concentrate urine is evaluated every hour, plasma sodium concentration is evaluated every 2 hours  
  • MRI of the head, revealing an abnormality in or near the pituitary gland  
  • Blood serum sodium/salt concentration may be high if the condition is untreated

Treatment

The cause of the underlying condition should be treated.

Vasopressin (desmopressin) will be administered either as a nasal spray, oral tablets, or injections under the skin. This controls the urine output and fluid balance, and prevents dehydration.

In mild cases, increased water intake may be all that is needed. If the thirst mechanism is not working (for example, if a part of the brain called the hypothalamus is damaged), a prescription for a certain amount of water intake may also be needed (usually 2-2.5 L per day) to ensure proper hydration.

Expectations (prognosis)

The outcome is dictated by the underlying disorder. If treated, diabetes insipidus does not cause severe problems or reduce life expectancy.

Complications

     
  • Dehydration  
  • Electrolyte imbalance  
  • Confusion and changes in mental status may develop if the condition is not treated. All patients with diabetes insipidus should wear a medic alert bracelet or necklace to alert care givers to this condition in an emergency situation

Calling your health care provider

Call your health care provider if symptoms indicate diabetes insipidus may be present.

Prevention

Many of the cases may not be preventable. Prompt treatment of infections, tumors and injuries may reduce risk.

Johns Hopkins patient information

Last revised: December 5, 2012
by Potos A. Aagen, M.D.

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