Diabetes insipidus is a rare condition that occurs when the kidneys are unable to conserve water during the process of filtering blood. This form of diabetes is different than diabetes mellitus or "sugar" diabetes. Both forms of diabetes are associated with excessive urination, but have different causes and treatments.
Diabetes insipidus is caused by a lack of antidiuretic hormone (ADH), also called vasopressin, which prevents dehydration, or the kidney's inability to respond to ADH. ADH enables the kidneys to retain water in the body. The hormone is produced in a region of the brain called the hypothalamus. It is stored and released from the pituitary gland, a small gland at the base of the brain.
When diabetes insipidus is caused by a lack of ADH, it is called central diabetes insipidus. This form of the disease can be caused by damage to the hypothalamus or pituitary gland.
When the condition is caused by a failure of the kidneys to respond to ADH, the condition is called nephrogenic diabetes insipidus, which may be inherited. This form of the disease involves a kidney defect that prevents the body from reabsorbing water back into the bloodstream. It is the rarest form of this uncommon disease.
The primary symptoms of diabetes insipidus is excessive thirst and excessive urination, sometims as often as every 15 minutes. This is caused by the lack of antidiuretic hormone (ADH), also called vasopressin, or the inability of the kidneys to respond to ADH.
Because of the excessive consumption of fluids, your urine may be very clear, like water. Most people with this condition become so thirsty that they drink enough water to prevent dehydrationreplace all of the fluid they urinate, and not become dehydrated.
To diagnose diabetes insipidus, your doctor will ask you questions about your health and that of other family members to create a detailed medical history, particularly is your doctor suspects you have the inherited form of the disease. Tests that may be administered include:
Urinalysis — This test examines the contents of your urine. If the water content is high and the salt and waste concentration low, it could be due to diabetes insipidus.
Fluid or Water Deprivation Test — This is a test to measure changes in your body weight, urine output and urine contents. Prior to this test, your doctor will measure your weigh and collect a urine sample for analysis. Your doctor will ask you to stop drinking fluids for several hours. During this period, urine samples will be collected. Your doctor also may measure the blood levels of antidiuretic hormone (ADH) or vasopressin. For children and pregnant women, it's important that no more than 5 percent of body weight is lost during the test.
The medication used to treat this disorder is called desmopressin acetate (DDAVP), which is similar to the hormone antidiuretic hormone (ADH), also called vasopressin, produced by your body. DDAVP comes in several forms. Your doctor will work with you to prescribe the one that works best for you. The different forms are:
Nasal Spray — This is medication is squirted into your nostril. A dose is usually taken at bedtime so you can sleep through the night uninterrupted. Some people may require a dose during the day.
Rhinal Tube Solution — This form of the medication is stored in the refrigerator at all times. A small tube tis used o deliver very precise doses of medication into your nose. Though the medication can be more difficult to deliver through the rhinal tube, you can vary the dose of the medication, as needed. It can be more helpful for those who have a varying schedule or who need very small doses. Both this form and the nasal spray are delivered into your nostril for very rapid absorption into the bloodstream. Clean your nostrils with a tissue before administration the medication for better absorption.
Reviewed by health care specialists at UCSF Medical Center.