diabetes insipidus is an uncommon disorder characterized by intense thirst, despite the drinking of fluids (polydipsia), and the excretion of large amounts of urine (polyuria). In most cases, it’s the result of your body not properly producing, storing or releasing a key hormone, but diabetes insipidus can also occur when your kidneys are unable to respond properly to that hormone.
Diabetes insipidus occurs when your body can’t regulate how it handles fluids. Normally, your kidneys remove excess body fluids from your bloodstream. This fluid waste is temporarily stored in your bladder as urine, before you urinate. When your fluid regulation system is working properly,your kidneys make less urine when your body water is decreased, such as through perspiration, to conserve fluid.
The volume and composition of your body fluids remain balanced through a combination of oral intake and excretion by the kidneys. The rate of fluid intake is largely governed by thirst, although your habits can increase your intake far above the amount necessary. The rate of fluid excreted by your kidneys is greatly influenced by the production of anti-diuretic hormone (ADH), also called vasopressin.
Your body makes ADH in the hypothalamus and stores the hormone in your pituitary gland, a small gland located in the base of your brain. ADH is released into your bloodstream when your body starts to become dehydrated. ADH then concentrates the urine by triggering the kidney tubules to release water back into your bloodstream rather than excreting as much water into your urine.
The way in which your system is disrupted determines which form of diabetes insipidus you have:
You may assume diabetes insipidus and diabetes mellitus — the more common form of diabetes involving blood sugar — are related. Although the disorders share a name and have some common signs,diabetes mellitus (type 1 and type 2) and diabetes insipidus are unrelated.
- Central diabetes insipidus. The cause of central diabetes insipidus in adults is usually damage to the pituitary gland or hypothalamus, most commonly due to surgery, a tumor, an illness (such as meningitis), inflammation or a head injury. For children, the cause is often an inherited genetic disorder. In some cases the cause is unknown. This damage disrupts the normal production, storage and release of ADH.