Diabetes insipidus (die-uh-BEE-teze in-SIP-uh-dus) 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. Rarely, diabetes insipidus can occur during pregnancy (gestational diabetes insipidus).
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.
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 range from 2 quarts (about 2 liters) a day if you have mild diabetes insipidus to 21 quarts (about 20 liters) a day if the condition is severe and if you're drinking a lot of fluids. In comparison, the average urine output for a healthy adult varies, but is in the range of 1.6 to 2.6 quarts (about 1.5 to 2.5 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
- Unusually wet diapers
- Fever, vomiting or diarrhea
- Dry skin with cool extremities
- 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 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:
- 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.
- 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 and demeclocycline (a tetracycline antibiotic), also can cause nephrogenic diabetes insipidus.
- Gestational diabetes insipidus. Gestational diabetes insipidus 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 can also be caused by 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
- Muscle weakness
- Low blood pressure (hypotension)
- Elevated blood sodium (hypernatremia)
- Sunken appearance to your eyes
- 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 pains
You're likely to start by seeing your family doctor or a general practitioner. However, in some cases when you call to set up an appointment you may be referred to a specialist called an endocrinologist.
Here's some information to help you get ready for your appointment.
What you can do
- Be aware of any pre-appointment restrictions. At the time you make the appointment, be sure to ask if there's anything you need to do in advance. Your doctor may ask you to stop drinking water the night before — do so only if your doctor asks you to.
- Write down any symptoms you're experiencing, including any that may seem unrelated to the reason for which you scheduled the appointment. Be prepared to answer specific questions about how often you urinate and how much water you drink each day.
- Write down key personal information, including any major stresses or recent life changes.
- Make a list of your key medical information, including recent surgical procedures, the names of all medications you're taking and any other conditions for which you've recently been treated. Your doctor will also want to know about any recent injuries to your head.
- Take a family member or friend along, if possible. Sometimes it can be difficult to soak up all the information provided to you during an appointment. Someone who accompanies you may remember something that you missed or forgot.
- Write down questions to ask your doctor.
For diabetes insipidus, some basic questions to ask your doctor include:
- What is likely causing my symptoms or condition?
- What other possible causes are there?
- What kinds of tests do I need?
- Is my condition likely temporary or chronic?
- What is the best course of action?
- How will you monitor whether my treatment is working?
- Will I need to make any changes to my diet or lifestyle?
- Will I still need to drink a lot of water if I'm taking medications?
- I have these other health conditions. How can I best manage them together?
- Are there any restrictions I need to follow?
- Is there a generic alternative to the medicine you're prescribing?
- Are there brochures or other printed material I can take home or websites you recommend?
Don't hesitate to ask questions during your appointment.
What to expect from your doctor
Your doctor is likely to ask you a number of questions, including:
- When did you begin experiencing symptoms?
- How much more are you urinating than usual?
- How much water do you drink each day?
- Do you get up at night to urinate and drink water?
- Are you pregnant?
- Are you being treated or have you recently been treated for other medical conditions?
- Have you had any recent head injuries or have you had neurosurgery?
- Has anyone in your family been diagnosed with diabetes insipidus?
- What, if anything, seems to improve your symptoms?
- What, if anything, appears to worsen your symptoms?
What you can do in the meantime
While you're waiting for your appointment, drink until your thirst is relieved, as often as necessary. Avoid activities that might cause dehydration, such as physical exertion or spending time in the heat.
Since the signs and symptoms of diabetes insipidus can be caused by other conditions, your doctor will perform a number of tests. 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 form of the disease.
Some of the tests doctors commonly use to diagnose and determine the type of diabetes insipidus and in some cases, its cause, include:
- Water deprivation test. This test confirms the diagnosis and helps determine the cause of diabetes insipidus. You'll be asked to stop drinking fluids several hours before the test 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. Your doctor may also measure blood levels of ADH or administer synthetic ADH during this test. The water deprivation test is performed under close supervision in children and pregnant women to make sure no more than 5 percent of body weight is lost during the test.
- Urinalysis. Urinalysis is the physical and chemical examination of urine. If your urine is less concentrated — meaning the amount of water is high relative to other excreted substances — it could be due to diabetes insipidus.
- 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.
If your doctor suspects an inherited form of diabetes insipidus, he or she will look at your family history of polyuria and may suggest genetic screening.
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. Because the cause of this form of diabetes insipidus is a lack of anti-diuretic hormone (ADH), treatment is usually with a synthetic hormone called desmopressin. You can take desmopressin as a nasal spray, as oral tablets or by injection. The synthetic hormone will eliminate the increase in urination. For most people with this form of the condition, desmopressin is safe and effective. If the condition is caused by an abnormality in the pituitary gland or hypothalamus (such as a tumor), your doctor will first treat the abnormality.
Desmopressin should be considered a medication you take as needed. This is because in most people, the deficiency of ADH is not complete, and the amount made by the body can vary day to day. Taking more desmopressin than needed can result in too much water retention and low sodium levels in the blood. Symptoms of low sodium include lethargy, confusion, nausea and, in severe cases, seizures.
In mild cases of central diabetes insipidus, you may need only to increase your water intake.
Nephrogenic diabetes insipidus. This condition is the result of your kidneys not properly responding to ADH, so desmopressin is not a treatment option. 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.The drug hydrochlorothiazide, used alone or with other medications, may improve symptoms. Although hydrochlorothiazide is a diuretic (usually used to increase urine output), in some cases it can reduce urine output for people with nephrogenic diabetes insipidus.
If symptoms from nephrogenic diabetes insipidus are due to medications you're taking, stopping these medicines may help; however, don't stop taking any medication without first talking to your doctor.
- 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 intake. However, if the condition is caused by mental illness, treating the mental illness may relieve the symptoms.
If you have diabetes insipidus:
- Prevent dehydration. As long as you take your medication and have access to water when the medication's effects wear off, you'll prevent serious problems. Plan ahead by carrying water with you wherever you go, and keep a supply of medication in your travel bag, at work or at school.
- Wear a medical alert bracelet or carry a medical alert card in your wallet. If you have a medical emergency, a health care professional will recognize immediately your need for special treatment.
Mar. 14, 2013
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