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Diabetes, B.P and Thyroid Vouchers
This information will give you and your family basic facts about diabetes insipidus. The glossary at the end defines certain terms used throughout. If you have questions about the diagnosis and treatment of this disorder, feel free to talk with your physician and nurse. They will be glad to help you.
What is diabetes insipidus?
Diabetes insipidus is a rare disorder of water metabolism. This means that the balance between how much water or fluid you drink is not balanced with the fluid you urinate. Diabetes insipidus is caused by a lack of, or nonresponse to, the antidiuretic hormone vasopressin. This hormone controls water balance by concentrating urine. Patients with diabetes insipidus urinate too much, so they need to drink a lot to replace the fluid they lose.
Vasopressin is made by the cells of the hypothalamus (located in the brain) and is stored and secreted by another part of the brain called the posterior pituitary gland. The antidiuretic hormone is then released into the bloodstream where it causes tubules within the kidney to reabsorb water. Water that cannot be reabsorbed is passed out of the body in the form of urine. Decreased secretion of vasopressin causes less water to be reabsorbed and more urine to be formed. When vasopressin is present at normal levels, more water is reabsorbed and less urine is formed.
You should not confuse diabetes insipidus with the metabolic disease, diabetes mellitus. Diabetes mellitus is a different disease caused by a lack of, or an impaired response to, the hormone insulin. This hormone is made by the pancreas and helps in carbohydrate metabolism.
Without insulin, a person cannot make use of the carbohydrates he or she takes in, such as sugar. The hormone insulin affects sugar so that it can enter the body's cells and be used for energy. When insulin is insufficient or not present, an abnormally high amount of sugar will be in the blood and urine. The chart at the end of this booklet explains in greater detail the difference between diabetes insipidus and diabetes mellitus.
There are two types of diabetes insipidus.
While the symptoms of these two disorders are similar, the causes are different.
Patient Information Publications 1 Diabetes Insipidus
Central diabetes insipidus
If you have been diagnosed with central diabetes insipidus,
There are some things you should know about how the disorder is caused and what you and your doctor can do about it.
What causes it?
In central diabetes insipidus, the antidiuretic hormone vasopressin is either missing or present at a low level. This low level or lack of vasopressin is due to a malfunction in the part of your brain, the posterior pituitary gland, which releases the hormone into your bloodstream. Injury to the head, tumors, neurosurgical operations, infections, or bleeding can affect your brain's ability to release the right amount of vasopressin.
What are the symptoms?
excessive urination (polyuria) which is followed by excessive thirst (polydipsia)
Patients with central diabetes insipidus are often extremely tired because they cannot get enough sleep uninterrupted by the need to urinate. Their urine is very clear and odorless. These symptoms can appear at any time. Because they lose so much water from urination, they also feel very thirsty. If this disorder is untreated, they could become seriously dehydrated, and their bodies will not have enough water to function properly.
Nephrogenic diabetes insipidus
Nephrogenic diabetes insipidus is much less common than central diabetes insipidus. If you have been diagnosed with nephrogenic diabetes insipidus, your doctor or nurse will discuss the disorder and its treatment with you. They will be happy to answer your questions.
What causes it?
Nephrogenic diabetes insipidus may be caused by kidney diseases that make the kidneys unable to respond to vasopressin. While there is enough vasopressin in the body (unlike in central diabetes insipidus), the kidneys cannot respond to the hormone's signal to reabsorb water. The disease may be acquired or inherited by male children.
What are the symptoms?
The symptoms of nephrogenic diabetes insipidus are similar to central diabetes insipidus; that is, excessive urination (polyuria) followed by excessive thirst (polydipsia).
How is it treated?
The first step in treating this disease is correct diagnosis. In addition to the medications available, balancing your water or fluid intake with your urine output is also part of treatment. If this disorder is untreated, you could become seriously dehydrated, and your body will not have enough water to function. Patient Information Publications 2 Diabetes Insipidus
What tests can find out if I have central diabetes insipidus or nephrogenic diabetes insipidus?
The two most common tests used to diagnose diabetes insipidus are the following:
Water deprivation test/vasopressin test
Hypertonic saline infusion test.
Other tests which may be used are the urine specific gravity test and the serum or urine osmolality test. These tests measure the concentration of solid particles in your urine. Patients with diabetes insipidus have urine with fewer solids than that of people without the disease.
With the water deprivation test, you will be asked not to drink any fluids. Your doctor will tell you how long you must abstain from drinking. Then, laboratory tests will be done to show any change in the amount and concentration of particles in your urine.
The vasopressin test is done if the water deprivation test does not result in sufficiently concentrated urine. Vasopressin is given by the doctor or nurse by injection to test your body's reaction to the hormone.
During the hypertonic saline infusion test, you will receive a mixture of salt and water by intravenous infusion. Your doctor or nurse will then draw blood from you which will be tested for osmolality and vasopressin content.
The serum or urine osmolality test is done to find out the concentration of particles in your blood or urine.
The urine specific gravity test is also a way to find out the concentration of solid particles in urine. Patients with diabetes insipidus have fewer particles in urine, so their specific gravity measurements will be below normal.
What is the therapy for central diabetes insipidus?
If you are treated for central diabetes insipidus, you will sniff a drug called DDAVP (Desmopressin), a derivative of vasopressin. You will be shown the right way to use this drug by your physician, nurse, or pharmacist.
What is the therapy for nephrogenic diabetes insipidus?
If you have nephrogenic diabetes insipidus, water pills (thiazide diuretics) may be prescribed by your doctor. You may be confused as to why you need to take diuretics for this disorder. Thiazide diuretics have been shown to stimulate the production of a hormone that helps your body retain salt. This added amount of salt keeps you from losing too much water.
And of course, always feel free to ask your doctor or nurse any questions you have about your diagnosis and treatment.