Diabetes insipidus (DI) is a rare condition that occurs when your kidneys are not able to conserve water. It results in extreme thirst for water and frequent urination. There are several types of DI, and they can often be successfully treated.
This condition is not related to diabetes mellitus (the disease most often referred to as simply “diabetes”).
Normal Fluid Regulation
To understand diabetes insipidus, it helps to understand how your body normally uses and regulates fluids.
Fluids make up as much as 60 percent of your overall body mass. Maintaining the proper amount of fluid in your body is key to your overall health. You must drink water to balance and regulate the fluid in your body.
In addition to your active intake of water and fluids, your body uses a system of organs and hormone signals to regulate body fluids. The kidneys play an important role in this fluid regulation by removing extra fluid from your bloodstream. The bladder stores this fluid waste until you urinate it out. Your body regulates fluid levels by making less urine when you need to replace fluid lost to sweating, or by making more urine when there is too much fluid in your body.
Your brain regulates this process in a few ways. The hypothalamus, a part of the brain, regulates your feeling of thirst and the need to drink water. The brain also produces an anti-diuretic hormone (ADH), called vasopressin, which is stored in the pituitary gland after production. When your body needs to retain water, the pituitary gland will release the vasopressin into the blood stream. When you need to get rid of water, the hormone is not release, and your kidneys will cause you to urinate more often.
When any part of this regulation system breaks down, it can lead to diabetes insipidus.
There are four types of DI:
Central Diabetes Insipidus
This is the most common form of DI and is caused by damage to the pituitary gland or hypothalmus. This damage means anti-diuretic hormone (ADH) cannot be produced, stored and/or released normally.
According to the National Kidney and Urologic Diseases Information Clearinghouse, this type of DI is often the result of head trauma, diseases that cause brain swelling, surgery, tumors, loss of blood supply to the pituitary, or rare genetic conditions (NKUDIC, 2012).
Nephrogenic Diabetes Insipidus
This is caused by damage to the kidneys that makes them unable to respond to the ADH.
It can also be caused by drugs (lithium or tetracycline), high levels of calcium in the body, or other medical conditions such as sickle cell disease, polycystic kidney disease, or rare genetic conditions.
Dipsogenic Diabetes Insipidus
This form of the disease is caused by dysfunction of the thirst mechanism in the brain (hypothalamus) resulting in drinking too much liquid. The exact cause is unclear, but associated conditions include mental illness and sarcoidosis (an inflammatory disease).
Gestational Diabetes Insipidus
This type of DI occurs only during pregnancy when an enzyme made by the placenta destroys a mother’s own ADH. The placenta plays an important role in the exchange of nutrients and waste products between the fetus and the mother.
In some cases the cause of DI may be difficult to determine.
The condition can occur in anyone, but in all cases except for gestational DI it usually affects males. Current studies suggest there may be a genetic link.
The main symptoms of DI are excessive thirst—you may have an uncontrollable craving for water—and excessive urine volume. According to the Mayo Clinic, your daily urine output may range from 2.6 quarts to 16 quarts. Normal urine output is 1.6 to 2.4 quarts per day (Mayo Clinic, 2010).
You may need to get up during the night to urinate frequently or you may experience bedwetting.
Possible symptoms in young children and infants include:
- fussiness and crying
- unusually wet diapers or bedwetting
- fever, vomiting, or diarrhea
- dry skin
- delayed growth
- weight loss
You should contact your healthcare professional immediately if you or your child are experiencing these symptoms.
Your doctor will talk to you about your symptoms and determine which tests are necessary. Your doctor may use several tests for diagnosis.
Your doctor will take a sample of your urine to test for salt and other waste concentrations. If you have DI, your urinalysis will have a high concentration of water and a low concentration of other waste.
Water Deprivation Test
You will stop drinking water for a specified period of time before the test. You will then give blood and urine samples, and your healthcare professional will measure changes in:
- blood sodium and osmolality levels
- body weight
- urine output
- urine composition
- ADH blood levels
The test is done under close supervision, and may require hospitalization in certain people to ensure it is done safely
Magnetic Resonance Imaging (MRI)
This uses a machine that will take an image of your brain tissue using magnets and radio waves. It will see if there is any damage to the brain tissue that is causing your symptoms. Your healthcare professional will look closely at your pituitary gland for any damage or abnormalities.
This may be performed to look for an inherited form of DI based on your family history.
Treatment will depend on which type of DI you are diagnosed with, and how severe your condition is. In mild cases of DI your doctor may recommend that you increase your water intake to a specific amount per day.
The most common form of treatment for all DI types is desmopressin. This is an artificial hormone that can be taken by pill, nasal spray, or injection. It is a synthetic form of the hormone vasopressin. While taking this medication, it is important to regulate your water intake and drink only when you are thirsty.
Desmopressin is often prescribed for severe gestational DI.
Drugs and Medication
In nephrogenic DI, treatment includes taking high doses of desmopressin, along with other drugs like hydrochlorothiazide or indomethacin, or a combination of medications called Moduretic. When taking these medications, it is important to drink water only when you are thirsty.
If the condition is due to medications you are taking, you will work with your healthcare professional to replace or stop taking these medications. However, do not stop taking any medication without talking with your healthcare professional first.
Treating Underlying Conditions
If your DI is caused by another condition such as a tumor or problem with the pituitary gland, your healthcare professional will treat that condition first and then determine if the DI still needs to be treated.
There isn’t a specific treatment for dipsogenic DI, but treating symptoms or primary mental illness may relieve the symptoms.
You may need to eat a low-salt diet to decrease the amount of urine your kidneys produce.
Lifestyle modifications are important in the treatment of DI. The most important of these is preventing dehydration. You can do this by bringing water with you wherever you go or offering water every few hours to your child if he or she is the one affected. Your doctor will help you determine just how much fluid you should be drinking each day.
Also, carrying a medical alert card in your wallet or wearing a medical bracelet can ensure that others know about your DI in case of an emergency. Because dehydration can happen quickly, those around you should know of your condition.
The prognosis depends on the underlying cause of the disorder. When it is treated properly, DI does not cause any severe or long-term complications.
The most common complication of DI is dehydration. It is important to recognize the symptoms of dehydration:
- dry mouth and skin
- muscle weakness
- low blood pressure
- rapid heart rate
- weight loss
- sunken appearance in eyes and soft spots of children
- muscle pains
In dipsogenic DI you may drink too much water, which can lead to water intoxication. In extremely rare cases, this can lead to brain damage because it lowers the sodium concentration in your body.