Diabetes Insipidus

Diabetes Insipidus (DI) should not be confused with diabetes mellitus (Read about "Diabetes"), which results from insulin deficiency or resistance. Diabetes insipidus and diabetes mellitus are unrelated, although they can have similar signs and symptoms, like excessive thirst and excessive urination.

According to the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), diabetes insipidus (DI) is characterized by excretion of large amounts of dilute urine, which disrupts your body's water regulation. (Read about "The Urinary System")

The body has a complex system for balancing the volume and composition of body fluids. Normally, according to NIDDK, the rate of fluid intake is governed by thirst, and the rate of excretion is governed by the production of antidiuretic hormone (ADH), also called vasopressin. This hormone is secreted by the pituitary gland, which releases it into the bloodstream when necessary. The pituitary is part of the endocrine system. (Read about "The Endocrine System") When ADH reaches the kidneys, it directs the kidneys to concentrate the urine by returning excess water to the bloodstream and therefore make less urine.

In DI, this system is disrupted. NIDDK says this can result from a number of things, including but not limited to:

• damage to the pituitary, which can be caused by different diseases as well as by head injuries (Read about "Head Injury"), neurosurgery or genetic disorders
• problems with the kidneys, which can be caused by drugs and by chronic disorders including kidney disease, polycystic kidney disease, sickle cell disease, partial blockage of the ureters and inherited genetic disorders (Read about "Kidney Disease" "Polycystic Kidney Disease" "Sickle Cell Disease")
• problems with the body's mechanism for thirst
• pregnancy (Read about "Healthy Pregnancy"), which causes a condition called gestational DI

Diagnosis of DI is based on a series of tests, including urinalysis and a fluid deprivation test. Treatment options, which can include hormonal therapy and/or surgery, depend on the specific cause of the problem. Different drugs are used, depending on whether the cause is the kidneys, the pituitary or pregnancy. NIDDK says drugs are not used if the problem lies with the thirst mechanism.