Diagnosis

Tests used to diagnose diabetes insipidus include:

• Water deprivation test. While being monitored by a doctor and health care team, you'll be asked to stop drinking fluids for several hours. To prevent dehydration while fluids are restricted, ADH allows your kidneys to decrease the amount of fluid lost in the urine.

  While fluids are being withheld, your doctor will measure changes in your body weight, urine output, and the concentration of your urine and blood. Your doctor may also measure blood levels of ADH or give you synthetic ADH during this test. This will determine if your body is producing enough ADH and if your kidneys can respond as expected to ADH.

• Magnetic resonance imaging (MRI). An MRI can look for abnormalities in or near the pituitary gland. This test is noninvasive. It uses a powerful magnetic field and radio waves to construct detailed pictures of brain tissues.
• Genetic screening. If others in your family have had problems with excess urination, your doctor may suggest genetic screening.