Diabetes insipidus (die-uh-BEE-teze in-SIP-uh-dus) is an uncommon disorder that causes an imbalance of water in the body. This imbalance leads to intense thirst even after drinking fluids (polydipsia), and excretion of large amounts of urine (polyuria).
While the names diabetes insipidus and diabetes mellitus sound similar, they’re not related. Diabetes mellitus — which can occur as type 1 or type 2 — is the more common form of diabetes. There’s no cure for diabetes insipidus, but treatments are available to relieve your thirst and normalize your urine output.
The most common signs and symptoms of diabetes insipidus are:
- Extreme thirst
- Excretion of an excessive amount of diluted urine
Depending on the severity of the condition, urine output can be as much as 16 quarts (about 15 liters) a day if you’re drinking a lot of fluids. Normally, a healthy adult will urinate an average of less than 3 quarts (about 3 liters) a day.
Other signs may include needing to get up at night to urinate (nocturia) and bed-wetting. Infants and young children who have diabetes insipidus may have the following signs and symptoms:
- Unexplained fussiness or inconsolable crying
- Trouble sleeping
- Delayed growth
- Weight loss
When to see a doctor
See your doctor immediately if you notice the two most common signs of diabetes insipidus: excessive urination and extreme thirst.
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 conserve fluid and make less urine when your body water is decreased, such as through perspiration.
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 known as 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:
- Central diabetes insipidus. The cause of central diabetes insipidus in adults is usually damage to the pituitary gland or hypothalamus. This damage disrupts the normal production, storage and release of ADH.The damage is commonly due to surgery, a tumor, an illness (such as meningitis), inflammation or a head injury. For children, the cause may be an inherited genetic disorder. In some cases the cause is unknown.
- Nephrogenic diabetes insipidus. Nephrogenic diabetes insipidus occurs when there’s a defect in the kidney tubules — the structures in your kidneys that cause water to be excreted or reabsorbed. This defect makes your kidneys unable to properly respond to ADH.The defect may be due to an inherited (genetic) disorder or a chronic kidney disorder. Certain drugs, such as lithium or the antiviral medications cidofovir and foscarnet (Foscavir), also can cause nephrogenic diabetes insipidus.
- Gestational diabetes insipidus. Gestational diabetes insipidus is rare and occurs only during pregnancy and when an enzyme made by the placenta — the system of blood vessels and other tissue that allows the exchange of nutrients and waste products between a mother and her baby — destroys ADH in the mother.
- Primary polydipsia. This condition — also known as dipsogenic diabetes insipidus or psychogenic polydipsia — can cause excretion of large volumes of dilute urine. Rather than a problem with ADH production or damage, the underlying cause is intake of excessive fluids.Prolonged excessive water intake by itself can damage the kidneys and suppress ADH, making your body unable to concentrate urine. Primary polydipsia can be the result of abnormal thirst caused by damage to the thirst-regulating mechanism, situated in the hypothalamus. Primary polydipsia has also been linked to mental illness.
In some cases of diabetes insipidus, doctors never determine a cause.
Nephrogenic diabetes insipidus that’s present at or shortly after birth usually has a genetic cause that permanently alters the kidneys’ ability to concentrate the urine. Nephrogenic diabetes insipidus usually affects males, though women can pass the gene on to their children.
Except for primary polydipsia, which causes you to retain too much water, diabetes insipidus can cause your body to retain too little water to function properly, and you can become dehydrated. Dehydration can cause:
- Dry mouth
- Changes in skin elasticity
- Low blood pressure (hypotension)
- Elevated blood sodium (hypernatremia)
- Rapid heart rate
- Weight loss
Diabetes insipidus can also cause an electrolyte imbalance. Electrolytes are minerals in your blood — such as sodium and potassium — that maintain the balance of fluids in your body. Electrolyte imbalance can cause symptoms, such as:
- Fatigue or lethargy
- Loss of appetite
- Muscle cramps