Diabetes insipidus, not to be confused with the more common diabetes mellitus, is a relatively rare disorder resulting from a failure to produce sufficient amounts of vasopressin, also known as antidiuretic hormone (ADH). Vasopressin, produced by the hypothalamus and secreted by the posterior pituitary gland, helps the kidneys to reabsorb water and maintain proper fluid balance. If the pituitary fails to produce enough ADH, water is not conserved but simply passed through the kidneys and excreted, typically in very large quantities.
More rarely, the kidneys fail to respond properly to ADH; this is known as nephrogenic diabetes insipidus. Dehydration is the primary health risk associated with either form. Diabetes insipidus affects both sexes equally. With proper treatment, overall prognosis is good (except in cases caused by cancer).
What Causes Diabetes Insipidus?
- In approximately one third of all cases, the cause of diabetes insipidus is unknown.
- Hereditary factors may play a role in some cases.
- Damage to the pituitary gland from a head injury, a hypothalmic tumor, or inflammation, radiation therapy, or surgery may lead to diabetes insipidus.
- The most frequent cause of nephrogenic diabetes insipidus is therapy with lithium.
- Blockage in an artery leading to the brain
Symptoms of Diabetes Insipidus
- Frequent and excessive urination (output may be as high as 25 to 35 quarts within 24 hours and may be as frequent as every 30 minutes, even at night)
- Extreme thirst
- Dry skin
- Emergency symptoms of dehydration, including dizziness, weakness, and unconsciousness
Prevention of Diabetes Insipidus
- There is no known way to prevent diabetes insipidus.
Diagnosis of Diabetes Insipidus
- Physical examination and patient history are performed. Diagnosis of diabetes insipidus is suspected when a patient reports unusually large and frequent urine output.
- A urinalysis is done to discover dilute urine (low specific gravity).
- A water deprivation test may be conducted. The patient consumes no fluids for eight hours while urine output and specific gravity are monitored. Patients with diabetes insipidus continue to produce large amounts of urine despite dehydration. An injection of vasopressin reduces urine volume and produces a concentrated urine in those with pituitary diabetes insipidus (but not nephrogenic diabetes insipidus).
- Magnetic resonance imaging (MRI) scan may be performed to detect pituitary abnormalities. In this test, a combination of large magnets, radiofrequency sound waves and a computer are used to produce detailed images of organs and structures within the body.
- Blood tests may be taken to assess water and salt balance.
How to Treat Diabetes Insipidus
- Vasopressin (synthetic ADH) may be administered (either in a nasal spray, as a pill, or by injection) to replace or supplement the body’s ADH production. Such hormone therapy is usually necessary for a lifetime, although if diabetes insipidus is caused by a head injury or surgery, it may be possible to discontinue treatment.
- To treat nephrogenic diabetes insipidus, your doctor may advise a low-salt diet to reduce thirst and slow the excretion of water. Certain diuretics may also be prescribed. (Nephrogenic diabetes insipidus does not respond to ADH treatment.)
- Drink plenty of fluids to prevent dehydration.
- Consume plenty of high-fiber foods and fruit juices to prevent or treat constipation.
When to Call a Doctor
- See a doctor immediately if you develop symptoms of diabetes insipidus.
- EMERGENCY Call an ambulance if you observe someone lose consciousness.
Johns Hopkins Symptoms and Remedies: The Complete Home Medical Reference
Simeon Margolis, M.D., Ph.D., Medical Editor
Prepared by the Editors of The Johns Hopkins Medical Letter: Health After 50
Updated by Remedy Health Media