Tests and diagnosis
Since the signs and symptoms of diabetes insipidus can be caused by other conditions, your doctor will perform a number of tests. If your doctor determines you have diabetes insipidus, he or she will need to determine which type of diabetes insipidus you have, because the treatment is different for each form of the disease. Some of the tests doctors commonly use to diagnose and determine the type of diabetes insipidus and in some cases, its cause, include:
- Water deprivation test. This test confirms the diagnosis and helps determine the cause of diabetes insipidus. You’ll be asked to stop drinking fluids several hours before the test so that your doctor can measure changes in your body weight, urine output and the concentration of your urine and blood when fluids are withheld. Your doctor may also measure blood levels of ADH or administer synthetic ADH during this test. The water deprivation test is performed under close supervision in children and pregnant women to make sure no more than 5 percent of body weight is lost during the test.
- Urinalysis. Urinalysis is the physical and chemical examination of urine. If your urine is less concentrated — meaning the amount of water is high relative to other excreted substances — it could be due to diabetes insipidus.
- Magnetic resonance imaging (MRI). An MRI of the head is a noninvasive procedure that uses a powerful magnetic field and radio waves to construct detailed pictures of brain tissues. Your doctor may want to perform an MRI to look for abnormalities in or near the pituitary gland.