Diabetes insipidus, or DI, is a very rare disease caused by a disruption in the body's signals to the kidneys to reabsorb fluids. The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), one of the National Institutes of Health, describes how a person with untreated DI is often excessively thirsty and has a frequent need to urinate. There are four types of diabetes insipidus, which are classified based on their respective causes.
Central Diabetes Insipidus
According to the NIDDK, central diabetes insipidus is the most common form of DI and is caused by damage to the pituitary gland. The pituitary gland is responsible for directing the hypothalamus to release a protein called antidiuretic hormone, often called vasopressin. Vasopressin instructs the kidneys to reabsorb fluid back into the body. When there is a defect in the production of vasopressin, the kidneys do not receive the proper signals to work correctly. The Diabetes Insipidus Foundation, a non-profit organization, notes that the causes of central DI include injury, infection, inherited diseases and cancer. However, they report that in over 50 percent of cases, the cause of damage to the pituitary gland is unknown.
Nephrogenic Diabetes Insipidus
The NDI Foundation, another non-profit organization, reports that nephrogenic DI is characterized by kidneys that are not responsive to the signals received from vasopressin. Thus, even though the pituitary gland correctly directs the release of vasopressin by the hypothalamus, and the vasopressin reaches the kidneys, the kidneys do not respond normally by reabsorbing fluid. The results, however, are the same as a damaged pituitary gland. Nephrogenic DI is usually caused by an inherited disease or by ingestion of substances that are toxic to the kidneys.
Dipsogenic Diabetes Insipidus
This type of diabetes insipidus is caused by a malfunction of the body's thirst mechanism, according to the NIDDK. When a person feels thirsty, it is the body's way of communicating that it is in need of more fluids. However, the body's thirst mechanism is increased in dipsogenic DI, resulting in excessive fluid intake, reduced vasopressin release and increased excretion of fluid by the kidneys. Currently, much about the causes and appropriate treatment of dipsogenic DI remains unknown.
Gestational DI
Gestational DI, according to NIDDK, affects only women who are pregnant. This type of DI is a result of vasopressin destruction by an enzyme produced by the placenta, which enables the exchange of nutrients and waste between the mother and the fetus. The lack of vasopressin results in the same lack of communication between the pituitary gland and the mother's kidneys as in Central DI. However, gestational DI disappears after the mother gives birth.
