Central diabetes insipidus

Definition

Central diabetes insipidus is a rare condition that involves extreme thirst and excessive urination.

See also: Diabetes insipidus - nephrogenic

Alternative Names

Causes

Central diabetes insipidus occurs when the body has too little of the hormone vasopressin.

Vasopressin normally limits the amount of urine the body produces. Normally, the hypothalamus gland in the brain makes vasopressin, and the pituitary gland stores the hormone. Without vasopressin, the kidneys do not work properly. The result is 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 make up for the water loss.

The reduced levels of vasopressin associated with central diabetes insipidus may be caused by damage to the hypothalamus or pituitary gland. This 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.

Symptoms

• Increased amount of urine production
• Excessive thirst
• Confusion and changes in consciousness (if the patient is unable to drink)

Exams and Tests

A person with central diabetes insipidus produces more than 3 liters of urine a day. Urinalysis will show a low concentration of salt in the urine.

A water restriction test is used to look at how well the kidney works and how much urine is produced. This test is done during a hospital stay. Results are checked every hour. A blood test to check plasma sodium concentration is done every 2 hours. Serum sodium/salt concentration may be high if the condition is untreated.

An MRI of the head may show a problem in or near the pituitary gland.

Treatment

The cause of the underlying condition should be treated.

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

In mild cases, drinking more water may be all that is needed. If the thirst mechanism is not working (for example, if 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.

Outlook (Prognosis)

The outcome depends on the underlying disorder. If treated, diabetes insipidus does not cause severe problems or result in early death.

Possible 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.

When to Contact a Medical Professional

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.

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