Central diabetes insipidus has several causes, including a brain tumor, a brain injury, brain surgery, tuberculosis, and some forms of other diseases.
The main symptoms are excessive thirst and excessive urine production.
The diagnosis is based on urine tests, blood tests, and a water deprivation test.
People with central diabetes insipidus usually are given the drugs vasopressin or desmopressin.
(See also Overview of the Pituitary Gland Overview of the Pituitary Gland The pituitary is a pea-sized gland that is housed within a bony structure (sella turcica) at the base of the brain. The sella turcica protects the pituitary but allows very little room for expansion... read more .)
Vasopressin is a hormone produced by the hypothalamus (a region of the brain that lies just above the pituitary) and stored in and released from the posterior lobe of the pituitary gland Overview of the Pituitary Gland The pituitary is a pea-sized gland that is housed within a bony structure (sella turcica) at the base of the brain. The sella turcica protects the pituitary but allows very little room for expansion... read more . Vasopressin helps regulate the amount of water in the body About Body Water Water accounts for about one half to two thirds of an average person’s weight. Fat tissue has a lower percentage of water than lean tissue and women tend to have more fat, so the percentage... read more by signalling the kidneys to decrease the amount of urine they produce. Because a diuretic is a substance that increases urine production, vasopressin previously was referred to as antidiuretic hormone.
Causes of Central Diabetes Insipidus
Central diabetes insipidus results from a deficiency of vasopressin. The deficiency may be
Caused by another disorder
Of unknown cause
Other disorders that can cause central diabetes insipidus include accidental damage done during surgery on the hypothalamus or pituitary gland; a brain injury, particularly a fracture of the base of the skull; a tumor; sarcoidosis Sarcoidosis Sarcoidosis is a disease in which abnormal collections of inflammatory cells (granulomas) form in many organs of the body. Sarcoidosis usually develops in people aged 20 to 40, most often people... read more or tuberculosis Tuberculosis (TB) Tuberculosis is a chronic contagious infection caused by the airborne bacteria Mycobacterium tuberculosis. It usually affects the lungs, but almost any organ can be involved. Tuberculosis... read more ; an aneurysm (a bulge in the wall of an artery) or blockage in the arteries leading to the brain; some forms of encephalitis or meningitis; and the rare disease Langerhans cell histiocytosis.
Nephrogenic diabetes insipidus Nephrogenic Diabetes Insipidus In nephrogenic diabetes insipidus, the kidneys produce a large volume of dilute urine because the kidney tubules fail to respond to vasopressin (antidiuretic hormone) and are unable to reabsorb... read more is another type of diabetes insipidus in which there is an adequate amount of vasopressin, but abnormalities in the kidneys cause them not to respond to vasopressin.
Symptoms of Central Diabetes Insipidus
Symptoms may begin gradually or suddenly at any age. Often the only symptoms are
Excessive urine production
The person urinates excessively and often wakes during the night to urinate. A person may drink huge amounts of fluid—4 to 40 quarts (3 to 30 liters) a day—to compensate for the fluid lost in urine. Ice-cold water is often the preferred drink. When compensation is not possible, dehydration Dehydration Dehydration is a deficiency of water in the body. Vomiting, diarrhea, excessive sweating, burns, kidney failure, and use of diuretics may cause dehydration. People feel thirsty, and as dehydration... read more can quickly follow, resulting in low blood pressure and shock. The person continues to urinate large quantities of dilute urine, and this excessive urination is particularly noticeable during the night.
Diagnosis of Central Diabetes Insipidus
Water deprivation test
Doctors suspect diabetes insipidus in people who produce large amounts of urine. They first test the urine for sugar to rule out diabetes mellitus Diabetes Mellitus (DM) Diabetes mellitus is a disorder in which the body does not produce enough or respond normally to insulin, causing blood sugar (glucose) levels to be abnormally high. Urination and thirst are... read more (a more common cause of excessive urination). Blood tests show abnormal levels of many electrolytes, including a high level of sodium.
The water deprivation test is the best test to diagnose central diabetes insipidus. In a water deprivation test, urine production, blood electrolyte levels, and weight are measured regularly for a period of about 12 hours, during which the person is not allowed to drink. A doctor monitors the person's condition throughout the course of the test. At the end of the 12 hours—or sooner if the person has a decrease in blood pressure, an increase in heart rate or a loss of more than 5% of body weight—the doctor stops the test and injects vasopressin. The diagnosis of central diabetes insipidus is confirmed if, in response to vasopressin, the person's excessive urination stops, the urine becomes more concentrated, the blood pressure rises, and the heart beats more normally. The diagnosis of nephrogenic diabetes insipidus is made if, after the injection, the excessive urination continues, the urine remains dilute, and blood pressure and heart rate do not change.
Treatment of Central Diabetes Insipidus
Desmopressin (a longer acting form of vasopressin) may be taken as a nasal spray twice a day or sometimes as a tablet or as an injection under the skin or into a vein (intravenously). The dose is adjusted to maintain the body's water balance and a normal urine output. Taking too much vasopressin can lead to fluid retention, swelling, and other problems. People with central diabetes insipidus who are undergoing surgery or are unconscious are generally given injections of vasopressin.
Sometimes central diabetes insipidus can be controlled with drugs that stimulate production of vasopressin, such as chlorpropamide, carbamazepine, clofibrate, and thiazide diuretics. These drugs are unlikely to relieve symptoms completely in people whose diabetes insipidus is severe.