diabetes insipidus

diabetes insipidus A metabolic disorder that mimics symptoms of diabetes mellitus, including increased output of urine and increased thirst. It is caused by a malfunction in the pituitary gland, and can be treated by administering vasopressin, a pituitary hormone. There are two types of diabetes insipidus, central and nephrogenic. Central diabetes insipidus is a lack of ADH production and is due to damage to the pituitary gland or hypothalamus where ADH is produced. Nephrogenic diabetes insipidus is a lack of response of the kidney to the fluid-conserving action of ADH. It can be due to diseases of the kidney (such as polycystic kidney disease), certain drugs (such as lithium), and can also occur as an inherited disorder. The main danger is when fluid intake does not keep pace with urine output, resulting in dehydration and high blood sodium. The treatment of central diabetes insipidus is with vasopressin. Nephrogenic diabetes insipidus does not respond to vasopressin treatment. In cases of nephrogenic diabetes insipidus caused by a drug (such as lithium), stopping the drug usually leads to recovery. In cases of hereditary nephrogenic diabetes insipidus, treatment is with fluid intake to match urine output and drugs that lower urine output. See also antidiuretic hormone; pituitary, posterior.