Diabetes insipidus is a rare disorder that causes an imbalance of water in the body. Even after drinking water, this imbalance leads to intense thirst even after drinking fluids (polydipsia), and excretion of large amounts of urine (polyuria).
Diabetes insipidus is not the same with diabetes mellitus. Diabetes mellitus which can occur as type 1 or type 2, is the more common form of diabetes.
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There’s no cure for diabetes insipidus, but treatments are available to relieve your thirst and normalize the output of your urine.
The most common signs and symptoms of diabetes insipidus are:
- Extreme thirst
- Urge to wake up at night and urinate
- 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) daily 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.
Infants and young children who have diabetes insipidus may have the following signs and symptoms:
- Difficulty sleeping
- Unexplained fussiness or inconsolable crying
- Weight loss
- Delayed growth
Causes of diabetes insipidus
Diabetes insipidus occurs when your body can’t control 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 pass out urine.
When your fluid regulation system is functioning properly, your kidneys conserve fluid and produce less urine when your body water is decreased, such as through sweat.
The volume and composition of your body fluids remain balanced through a combination of oral consumption and excretion by the kidneys. The rate of fluid consumption 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 produces ADH in the hypothalamus and stores the hormone in your pituitary gland. ADH is released into your bloodstream when your body begins to get dehydrated. ADH then concentrates the urine by triggering the kidney tubules to release water back into your bloodstream rather than passing out much water into your urine.
The way in which your system is disrupted determines which form of diabetes insipidus you have:
- Central diabetes insipidus: This occurs in adults and usually cause damage to the pituitary gland or hypothalamus. This damage disrupts the normal production, storage and release of ADH.
The damage is commonly as a result of surgery, a tumor, meningitis, inflammation or a head injury. For children, the cause may be an inherited genetic disorder.
- Nephrogenic diabetes insipidus:This occurs when there’s a fault 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:This type is rare and occurs only during pregnancy and when an enzyme made by the placenta 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 is also known as dipsogenic diabetes insipidus or psychogenic polydipsia. It can cause excretion of large volumes of dilute urine. Rather than a problem with ADH production or damage, the underlying cause is drinking of excessive fluids.
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Prolonged excessive drinking of water 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.
Nephrogenic diabetes insipidus usually has a genetic cause that permanently alters the ability of the kidneys to concentrate the urine. Nephrogenic diabetes insipidus usually affects males, though women can pass the gene on to their children.
Dinsipidus 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
- Weight loss
- Rapid heart rate
- Low blood pressure (hypotension)
- Elevated blood sodium (hypernatremia)
- Fever and headache
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
- Muscle cramps
- Loss of appetite
Since the signs and symptoms of diabetes insipidus can be caused by other conditions, your doctor will perform a number of tests to rule out other likelihoods. If your doctor determines you have diabetes insipidus, he or she will need to determine which type of diabetes insipidus you have, because the treatment is different for each type.
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Some of the tests may include:
- Water deprivation test.This test helps determine the cause of diabetes insipidus. Under medical supervision, you’ll be asked to stop drinking fluids for a time so that your doctor can measure changes in your body weight, urine output and the concentration of your urine and blood when fluids are withheld.
- This involves the physical and chemical examination of urine. If your urine is less concentrated, meaning the amount of water is high compared to other excreted substances.
- Magnetic resonance imaging (MRI).An MRI of the head is a noninvasive procedure that uses a powerful magnetic field and radio waves to construct detailed pictures of brain tissues. Your doctor may want to perform an MRI to look for abnormalities in or near the pituitary gland.
Treatment of diabetes insipidus depends on what form of the condition you have. Treatment options for the most common types of diabetes insipidus include:
- Central diabetes insipidus.Treatment is usually with a synthetic hormone called desmopressin. You can take desmopressin as oral tablets, injection or a nasal spray. The synthetic hormone will eliminate the increase in urination. For most people with this form of the condition, desmopressin is safe and effective.
- Nephrogenic diabetes insipidus.This condition is the result of your kidneys not responding to ADH, so desmopressin is not a treatment option in this case. Instead, your doctor may prescribe a low-salt diet to help reduce the amount of urine your kidneys make. You’ll also need to drink enough water to avoid dehydration.
- Gestational diabetes insipidus.Treatment for most cases of gestational diabetes insipidus is with the synthetic hormone desmopressin. In rare cases, this form of the condition is caused by an abnormality in the thirst mechanism. In these rare cases, doctors don’t prescribe desmopressin.
- Primary polydipsia.There is no specific treatment for this form of diabetes insipidus, other than decreasing the amount of fluid consumption.