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Genetic and Rare Diseases Information Center (GARD)

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Syndrome of inappropriate antidiuretic hormone


* Not a rare disease
Other Names for this Disease
  • Dilutional hyponatremia
  • Inappropriate ADH syndrome
  • Schwartz Bartter syndrome
  • Syndrome of inappropriate antidiuretic hormone secretion
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Your Question

The doctor told me I have SIADH or syndrome of inappropriate antidiuretic hormone. I would like to know more about it.

Our Answer

We have identified the following information that we hope you find helpful. If you still have questions, please contact us.

What is antidiuretic hormone?

Antidiuretic hormone is a hormone stored in the pituitary gland in the brain.[1] It is involved in regulating sodium levels in the blood and water volume in the body.[2] The release of antidiuretic hormone is controlled  by cells called osmoreceptors and baroreceptors. Osmoreceptors are specialized areas in a part of the brain called the hypothalamus.[1] These cells sense the concentration of particles in the blood. When the concentration is high, the pituitary releases more antidiuretic hormone. This causes more water to be retained to dilute the body fluids. When the concentration is low, the pituitary releases less antidiuretic hormone.[1]

The heart can also signal the pituitary to release more antidiuretic hormone when blood volume or blood pressure are low and less antidiuretic hormone when they are high.[1] In addition dehydration, pain, stress, exercise, low sugar levels, tumors, and certain drugs can stimulate the release of this hormone.[2]

Last updated: 5/16/2008

What is syndrome of inappropriate antidiuretic hormone?

Syndrome of inappropriate antidiuretic hormone (SIADH) occurs when an excessive amount of antidiuretic hormone is released resulting in water retention and a low sodium level. It is most common among older people. It has many causes including, but not limited too, heart failure, disorders of the hypothalamus, meningitis, encephalitis, psychosis, lung disorders (e.g., pneumonia) and cancer.[2]
Last updated: 5/16/2008

What are the symptoms of syndrome of inappropriate antidiuretic hormone?

Symptoms of syndrome of inappropriate antidiuretic hormone include water retention and low sodium level. Low sodium levels may cause lethargy and confusion. Severe low levels of sodium in the body may cause muscle twitching, seizures, stupor, coma, and death.[2]
Last updated: 5/16/2008

How might the syndrome of inappropriate antidiuretic hormone be treated?

Treatment of syndrome of inappropriate antidiuretic hormone (SIADH) may involve fluid restriction, treatment of the underlying cause once determined, and medication that decreases the effect of antidiuretic hormone on the kidneys. [2]
Last updated: 5/16/2008

What causes syndrome of inappropriate antidiuretic hormone?

Many things can cause syndrome of inappropriate antidiuretic hormone (SIADH), including brain injury, brain infection, brain abscesses, subarachnoid hemorrhage, encephalitis, meningitis, Guillain-Barré syndrome, delirium tremens, multiple sclerosis, lung cancer, pancreatic cancer, thymoma, ovarian cancer, lymphoma,  pneumonia, chronic obstructive pulmonary disease, lung abscess, tuberculosis, cystic fibrosis, surgery, and drugs.[3][4]

SIADH has also been reported in association with AIDS, temporal arteritis, polyarteritis nodosa, sarcoidosis, Rocky Mountain spotted fever, carcinoma of the cervix, olfactory neuroblastoma, and herpes zoster infection of the chest wall.[3]

Often the underlying cause of the condition can not be determined. In these cases the condition is said to be idiopathic.

Last updated: 5/16/2008