Diabetes insipidus (DI) is a condition characterized by excretion of large amounts of severely diluted urine, which cannot be reduced when fluid intake is reduced. It denotes inability of the kidney to concentrate urine. DI is caused by a deficiency of antidiuretic hormone (ADH), also known as vasopressin, or by an insensitivity of the kidneys to that hormone. It can also be induced iatrogenically by the diuretic conivaptan.
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Two things cause diabetes insipidus. In some people, a part of the brain (called the hypothalamus) doesn't make enough antidiuretic hormone (called ADH). ADH helps your body balance water in the urine and blood. In other people, the kidneys don't work with this hormone the way they should. Most people with diabetes insipidus get it after an injury to the head or after brain surgery. Some people with diabetes insipidus have a brain tumor. Sometimes it runs in families. Some medicines, like lithium, can also cause it. About 25% of the time, doctors can't find the cause.
Usually your doctor will check your urine to see how much water is in it. He or she may also check your blood. Your doctor may give you a "water deprivation" test. During this test, you aren't allowed to drink any liquids. The staff will weigh you, check your urine and blood every hour for several hours. If the results of the test show that you have diabetes insipidus, you will probably also have pictures taken of your brain with a CT (computed tomographic) scan or an MRI (magnetic resonance image). The scans can show problems in the brain.
If you aren't bothered by the symptoms, you might not have to do anything. However, your doctor will want to check on you more often. Also, you should make sure you always have something to drink, so your body doesn't get dehydrated (dried out).
Medicine can help if you have to get up often at night to urinate. One medicine called desmopressin (brand name: DDAVP) can help and it's like your body's natural ADH. This medicine comes as nasal spray and other forms. If you take DDAVP, you shouldn't drink too much, or your body will get overloaded with fluids. Too much fluid in your body and make you feel sick, weak or dizzy.
If your diabetes insipidus is caused by kidneys that don't work well with ADH, then DDAVP won't help. Other medicines, like hydrochlorothiazide (a "water" pill), may help. Water pills help your body balance salt and water.
Talk to your doctor about which option is right for you.
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