National Center for Advancing and Translational Sciences Genetic and Rare Diseases Information Center, a program of the National Center for Advancing and Translational Sciences

Syndrome of inappropriate antidiuretic hormone

Not a rare disease Not a rare disease
Other Names:
SIADH; Syndrome of inappropriate antidiuretic hormone secretion; Dilutional hyponatremia; SIADH; Syndrome of inappropriate antidiuretic hormone secretion; Dilutional hyponatremia; Schwartz Bartter syndrome; Inappropriate ADH syndrome See More
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.[1]
Last updated: 6/5/2014
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.[1]
Last updated: 6/5/2014

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. This information comes from a database called the Human Phenotype Ontology (HPO) . The HPO collects information on symptoms that have been described in medical resources. The HPO is updated regularly. Use the HPO ID to access more in-depth information about a symptom.

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Medical Terms Other Names
Learn More:
HPO ID
Percent of people who have these symptoms is not available through HPO
Decreased circulating renin level 0003351
Decreased serum creatinine
Low blood creatinine level
Reduced creatinine levels
[ more ] 		0012101
Elevated systolic blood pressure 0004421
Hypernatriuria 0012605
Hyponatremia
Low blood sodium levels
0002902
Irritability
Irritable
0000737
Seizure 0001250
X-linked recessive inheritance 0001419
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Last updated: 7/1/2020

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.[2]

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.[2]

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

Last updated: 6/5/2014
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. [1]
Last updated: 6/5/2014

If you need medical advice, you can look for doctors or other healthcare professionals who have experience with this disease. You may find these specialists through advocacy organizations, clinical trials, or articles published in medical journals. You may also want to contact a university or tertiary medical center in your area, because these centers tend to see more complex cases and have the latest technology and treatments.

If you can’t find a specialist in your local area, try contacting national or international specialists. They may be able to refer you to someone they know through conferences or research efforts. Some specialists may be willing to consult with you or your local doctors over the phone or by email if you can't travel to them for care.

You can find more tips in our guide, How to Find a Disease Specialist. We also encourage you to explore the rest of this page to find resources that can help you find specialists.

Healthcare Resources

Research helps us better understand diseases and can lead to advances in diagnosis and treatment. This section provides resources to help you learn about medical research and ways to get involved.

Clinical Research Resources

  • ClinicalTrials.gov lists trials that are related to Syndrome of inappropriate antidiuretic hormone. Click on the link to go to ClinicalTrials.gov to read descriptions of these studies.

    Please note: Studies listed on the ClinicalTrials.gov website are listed for informational purposes only; being listed does not reflect an endorsement by GARD or the NIH. We strongly recommend that you talk with a trusted healthcare provider before choosing to participate in any clinical study.

These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

Where to Start

  • MedlinePlus was designed by the National Library of Medicine to help you research your health questions, and it provides more information about this topic.
  • The Merck Manual provides information on this condition for patients and caregivers. 

In-Depth Information

  • Medscape Reference provides information on this topic. You may need to register to view the medical textbook, but registration is free.
  • MeSH® (Medical Subject Headings) is a terminology tool used by the National Library of Medicine. Click on the link to view information on this topic.
  • Online Mendelian Inheritance in Man (OMIM) is a catalog of human genes and genetic disorders. Each entry has a summary of related medical articles. It is meant for health care professionals and researchers. OMIM is maintained by Johns Hopkins University School of Medicine. 
  • Orphanet is a European reference portal for information on rare diseases and orphan drugs. Access to this database is free of charge.
  • PubMed is a searchable database of medical literature and lists journal articles that discuss Syndrome of inappropriate antidiuretic hormone. Click on the link to view a sample search on this topic.

Questions sent to GARD may be posted here if the information could be helpful to others. We remove all identifying information when posting a question to protect your privacy. If you do not want your question posted, please let us know. Submit a new question

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


  1. Lewis JL. Hyponatremia (Low Level of Sodium in the Blood). The Merck Manual Home Health Handbook. July 2013; http://www.merckmanuals.com/home/hormonal_and_metabolic_disorders/electrolyte_balance/hyponatremia_low_level_of_sodium_in_the_blood.html. Accessed 6/5/2014.
  2. Thomas CP. Syndrome of Inappropriate Antidiuretic Hormone Secretion. Medscape Reference. April 29, 2014; http://emedicine.medscape.com/article/246650-overview. Accessed 6/5/2014.