| Diabetes inspidus (DI) is a disorder that causes increased urination (polyuria) and increased thirst. It is caused by either a decrease in the hormone arginine vasopressin (central DI), or because the kidney does not respond correctly to the hormone (nephrogenic DI). Arginine vasopressin is a hormone that normally stimulates the collecting ducts of the kidney to reabsorb water, so if it is not able to work correctly, the kidney produces a very large volume of dilute urine.
Arginine vasopressin is normally produced in the hypothalamus, and so there can be a decrease in the its production caused by any condition that disrupts the hypothalamus, including brain tumors and head trauma, and some inherited conditions (septo-optic dysplasia). Nephrogenic DI can either be inherited or it can be a side effect of some medications, including Lithium, and some chronic conditions, such as sickle cell anemia, pyelonephritis, and urinary tract obstructions.
In addition to increased thirst and urination, other symptoms can include irritability, poor growth, nocturnal enuresis (wetting the bed at night), and if your child is not able to drink enough fluids to keep up with the large amount of fluid being lost from excessive urination, then your child may develop dehydration.
Testing can show a dilute urine, and a high level of sodium in the blood (hypernatremia), and concentrated serum with a high osmolarity. In children that have been drinking enough to keep up with losses, blood testing may be normal. A water deprivation test can sometimes be done, in which a child is not allowed to drink anything for 3 hours and his blood is checked to see if it has become more concentrated, and his urine is checked to see if it remains dilute. He may also be tested by giving a dose of DDAVP, which is a form of arginine vasopressin that can be given as a nose spray, to see if he has a response to it, which would be production of more concentrated urine.
Treatment of central DI is usually with DDAVP, a form of arginine vasopressin that can be given as a nose spray.
Diabetes Insipidus Internet Resources:
- Nephrogenic Diabetes Insipidus Foundation: The NDI Foundation was formed to support education, research, treatment and cure for Nephrogenic Diabetes Insipidus. Our goal is to create a communication channel to serve the entire NDI community: patients and their families, researchers, physicians and other health care providers.
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