Diabetes insipidus is a disorder in which a person experiences increased production of urine that is much more diluted than normal, according to the Diabetes Insipidus Foundation, a non-profit foundation devoted to the treatment and prevention of diabetes insipidus. People with diabetes insipidus often feel very thirsty, either as a direct result of the disease, or as an indirect result of too much fluid being excreted from the body. There are four main types of diabetes insipidus: central, gestational, dipsogenic, and nephrogenic.
Central Diabetes Insipidus
Central diabetes insipidus is caused by a damaged pituitary gland and/or hypothalamus. According to Merck Manuals, an online medical library, a hormone called antidiuretic hormone, or ADH, is made in the hypothalamus, then stored and secreted by the pituitary gland. If the cells in the hypothalamus responsible for making ADH, or the cells of the pituitary gland responsible for storing and/or secreting ADH are damaged, the result is central diabetes insipidus. The ADH protein travels through the circulatory system and signals the kidneys to reabsorb fluid back into the body instead of excreting it in urine. As a result, the urine becomes more concentrated with salts that the kidney excretes. With no ADH to signal the kidneys, fluid is not retained, and large amounts of diluted urine are delivered to the bladder, influencing a person to make frequent trips to the bathroom.
Gestational Diabetes Insipidus
Gestational diabetes insipidus affects some women while they are pregnant, and is caused by too little ADH circulating in the blood, according to the Diabetes Insipidus Foundation. While the hypothalamus and pituitary gland of these women are usually operating normally, the placenta of women with gestational diabetes insipidus produces an enzyme that destroys circulating ADH. The result is the same as central diabetes insipidus, where the kidneys excrete too much fluid. The enzyme may also cross the placenta and destroy the fetus's ADH, causing the baby to have diabetes insipidus as well.
Dipsogenic Diabetes Insipidus
This type of diabetes insipidus is caused by damage in the part of the brain that regulates thirst, according to the Clinical Center of the National Institutes of Health. The localized brain damage causes the person to feel chronically thirsty, and thus, the person drinks an excess of fluids. As a result, the production of ADH is suppressed, and the body excretes the excess fluid that is ingested.
Nephrogenic Diabetes Insipidus
In nephrogenic diabetes insipidus, the cells of a person's kidney are resistant to the effects of ADH, according to the Clinical Center of the National Institutes of Health. Thus, though ADH is secreted normally, the kidneys do not respond normally by reabsorbing fluid. This lack of reabsorption results in excess fluid excretion by the kidneys in the form of diluted urine. A specific gene that is passed from parent to child causes nephrogenic diabetes insipidus, affecting males more often than females.
