It is not possible to diagnose DI until the symptoms of excessive thirst and urination are present.  The diagnosis is initially evaluated by determining the daily intake and output of fluids and then measuring blood and urine water balance after a seven hour or longer period of water deprivation.  In some laboratories, the urinary measurement of vasopressin, after a water fast, can be used to diagnose DI.  A radiologic test called an MRI (magnetic resonance imaging) can demonstrate changes in the brain and pituitary area with DI, though an MRI cannot, by itself, diagnose DI.  More research is necessary to correlate changes seen in the brain with the occurrence of DI but it is hoped that the test will improve the capability of evaluating patients with DI.

The condition is usually corrected by giving synthetic vasopressin.  It is administered by placing some in a small plastic tube and gently blowing the liquid into the nostril where it is readily absorbed by the tissue of the nose lining.  Vasopressin is also available in a nose sprayer and by pill.  Dosage varies according to type.  Fortunately, the synthetic hormone is transportable and can be taken on trips, kept in the nurse's office in school, and for other occasions when out of the home.  Be sure to read instructions about the proper way to store the vasopressin. The role of radiotherapy and systemic chemotherapy in treating the lesion around the pituitary is still under study.  In most cases when these therapies have been tried, it has been impossible to reverse the condition.