Syndrome of Inappropriate Antidiuretic Hormone (SIADH)


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, pain, stress, exercise, a low blood sugar level, certain disorders of the heart, thyroid gland, kidneys, or adrenal glands, and the use of certain medications. Disorders of the lungs and certain cancers may increase the risk of developing SIADH. Treatment includes fluid restriction and sometimes the use of medications that decrease the effect of antidiuretic hormone on the kidneys.


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.

This table lists symptoms that people with this disease may have. For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed.

Medical TermsOther Names
Decreased circulating renin level
Decreased serum creatinineLow blood creatinine level
Reduced creatinine levels
Elevated systolic blood pressure
HyponatremiaLow blood sodium levels
X-linked recessive inheritance


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.

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.

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


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.

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United States. National Institutes of Health. Genetic and Rare Diseases Information Center. "Syndrome of Inappropriate Antidiuretic Hormone." June 5, 2014. <>.

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