Diabetes insipidus
Contents
When to Contact a Medical Professional
Diabetes insipidus is an uncommon condition in which the kidneys are unable to prevent the excretion of water.
Causes
During the day, your kidneys filter all your blood many times. Normally, most of the water is reabsorbed, and only a small amount of concentrated urine is excreted. DI occurs when the kidneys cannot concentrate the urine normally, and a large amount of dilute urine is excreted.
The amount of water excreted in the urine is controlled by antidiuretic hormone (ADH). ADH is also called vasopressin. ADH is produced in a part of the brain called the hypothalamus. It is then stored and released from the pituitary gland. This is a small gland at the base of the brain.
DI caused by a lack of ADH is called central diabetes insipidus. When DI is caused by a failure of the kidneys to respond to ADH, the condition is called nephrogenic diabetes insipidus.
Central diabetes insipidus can be caused by damage to the hypothalamus or pituitary gland as a result of:
- Genetic problems
- Head injury
- Infection
- Loss of blood supply to the gland
- Surgery
- Tumor
Nephrogenic DI involves a defect in the kidneys. As a result, the kidneys do not respond to ADH. Like central DI, nephrogenic DI is very rare. Nephrogenic DI may be caused by:
- Certain drugs (such as lithium)
- Genetic problems
- High level of calcium in the body (hypercalcemia)
- Kidney disease (such as polycystic kidney disease)
Symptoms
Symptoms of DI include:
- Excessive thirst that may be intense or uncontrollable, usually with the need to drink large amounts of water or craving for ice water
- Excessive urine volume
- Excessive urination, often needing to urinate every hour throughout the day and night
Exams and Tests
The health care provider will ask about your medical history and symptoms.
Tests that may be ordered include:
- Blood sodium and osmolarity
- Desmopressin (DDAVP) challenge
- MRI of the head
- Urinalysis
- Urine concentration
- Urine output
Treatment
The cause of the underlying condition will be treated when possible.
Central diabetes insipidus may be controlled with vasopressin (desmopressin, DDAVP). You take vasopressin as either an injection, a nasal spray, or tablets.
If nephrogenic DI is caused by medication, stopping the medication may help restore normal kidney function. But with some medications, such as lithium, after many years of use, nephrogenic DI can be permanent.
Hereditary nephrogenic DI and lithium-induced nephrogenic DI are treated by drinking enough fluids to match urine output. Medicines that lower urine output also need to be taken.
Nephrogenic DI is treated with anti-inflammatory medicines and diuretics (water pills).
Outlook (Prognosis)
Outcome depends on the underlying disorder. If treated, diabetes insipidus does not cause severe problems or result in early death.
Possible Complications
If your body's thirst control is normal and you drink enough fluids, there are no significant effects on body fluid or salt balance.
Not drinking enough fluids can lead to dehydration and electrolyte imbalance.
If DI is treated with vasopressin and your body's thirst control is not normal, drinking more fluids than your body needs can cause dangerous electrolyte imbalance.
When to Contact a Medical Professional
Call your health care provider if you develop symptoms of diabetes insipidus.
If you have diabetes insipidus, contact your health care provider if frequent urination or extreme thirst return.
Source: http://www.nlm.nih.gov/medlineplus/ency/article/000377.htm