Diabetes Basics

Insipidus: A Rare But Troublesome Form Of Diabetes

Diabetes insipidus (DI) is a rare kind of diabetes that causes frequent urination. The large volume of urine is diluted, mostly water. To make up for lost water, one may end up drinking large amounts of water. In this condition the patient urinates frequently, even at night, which can disrupt sleep or cause bed wetting occasionally. Excessive excretion of abnormally large volumes of dilute urine may result in dehydration if the patient doesn't drink enough water. Children with DI may be irritable or listless and may have fever, vomiting, or diarrhea.

Although diabetes insipidus and diabetes mellitus are unrelated, they can have similar signs and symptoms, like excessive thirst and excessive urination.

When fluid regulation system works properly, kidneys make less urine to conserve fluid when the body is losing water. When this precise system for regulating the kidneys' handling of fluids is disrupted, diabetes insipidus occurs. Central DI is the most common form of DI resulting from damage to the pituitary gland that disrupts normal release and storage of ADH. To treat the ADH deficiency a synthetic hormone called desmopressin can be taken by an injection, a nasal spray, or a pill.

Another form of DI is Nephrogenic DI. It is a result of kidney's inability to respond to ADH because of various disorders including polycystic kidney disease, sickle cell disease, and kidney failure. A drug called hydrochlorothiazide (also called HCTZ) or indomethacin is used for it's cure. HCTZ is sometimes combined with another drug called amiloride.

Dipsogenic DI is a third type caused by a defect in or damage to the thirst mechanism, which is located in the hypothalamus. This defect results in an abnormal increase in thirst and fluid intake that suppresses ADH secretion and increases urine output. This fluid "overload" can lead to water intoxication, a condition that lowers the concentration of sodium in the blood and can seriously damage the brain.

A fourth type of DI occurs only during pregnancy. Gestational DI occurs when an enzyme made by the placenta destroys ADH in the to be mother. Most cases of gestational DI can be treated with desmopressin. In rare cases, however, an abnormality in the thirst mechanism causes gestational DI, and desmopressin should not be used.

With the help of urine analysis and fluid deprivation test, DI can be diagnosed. The urine of a person with DI will be less concentrated. A physician evaluates the concentration of urine by measuring how many particles are present in a kilogram of water or by comparing the weight of the urine to an equal volume of distilled water (specific gravity). Fluid deprivation test helps determine whether DI is caused by excessive intake of fluid, a defect in ADH production, or due to a defect in the kidneys' response to ADH.

Although it's a rare disease, one must notice it's symptoms as it may even lead to grave consequences.