Definition
Diabetes insipidus is a condition where water in the body is improperly removed from the circulatory system by the kidneys.
There are two forms of diabetes insipidus (DI):
- Central diabetes insipidus (central DI)
- Nephrogenic diabetes insipidus (NDI)—due to renal cells in the kidneys not responding to ADH
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Causes
Antidiuretic hormone (ADH) controls the amount of water reabsorbed by the kidneys. ADH is made in the hypothalamus of the brain. The pituitary gland, at the base of the brain, stores and releases ADH. Central DI occurs when the hypothalamus does not make enough ADH. NDI occurs when the kidneys do not respond to ADH.
Some diabetes insipidus is casued by genetic problems that lead to central DI or NDI. Others may develop after an injury or illness.
Risk Factors
Factors that may increase your risk of diabetes insipidus include:
- Damage to the hypothalamus or pituitary glands due to surgery, infection, tumor , or head injury
- Certain conditions (eg, sarcoidosis , tuberculosis , granulomatosis with polyangiitis)
- Certain medicines (eg, lithium)—the most common cause of diabetes insipidus
- Kidney disease (eg, polycystic kidney disease )
- Protein malnutrition
- Certain conditions (eg, hypercalcemia, hypokalemia)
Symptoms
Symptoms may include:
- Increased urination, especially during the night
- Extreme thirst
- Dehydration (fast heart rate, dry skin and mouth)
Diagnosis
Your doctor will ask about your symptoms and medical history. A physical exam may be done.
Tests may include the following:
-
Blood tests
- Electrolyte levels
- Kidney function tests
- ADH levels
- Blood sugar to look for diabetes mellitus
-
Urinalysis
- Urine specific gravity and/or osmolality (measures how concentrated or dilute the urine is)
- Urine volume tests to see how much urine is being produced
-
Water deprivation test
- Only done under doctor supervision
- Urine output is measured for a 24-hour period