Nephrogenic Diabetes Insipidus
Nephrogenic diabetes insipidus is a disorder in which a defect in the small tubes (tubules) in the kidneys causes a person to produce a large amount of urine. Nephrogenic diabetes insipidus occurs when the kidney tubules, which allow water to be removed from the body or reabsorbed, do not respond to a chemical in the body called antidiuretic hormone (ADH) or vasopressin. ADH normally tells the kidneys to make the urine more concentrated. As a result of the defect, the kidneys release an excessive amount of water into the urine, producing a large quantity of very dilute urine. The most common symptoms are frequent urination (polyuria), especially during nighttime (nocturia), and drinking too much liquids (polydipsia). It can be either acquired or hereditary. The acquired form is brought on by certain drugs and chronic diseases and can occur at any time during life. About 90% of all cases of hereditary nephrogenic diabetes insipidus result from mutations in the AVPR2 gene, and about 10% of cases are caused by mutations in the AQP2 gene. Treatment consists of plenty of water intake; medication, such as thiazide diuretics and NSAIDs; and a low-salt, low-protein diet.