Summary
Definition
History and exam
Key diagnostic factors
- absence of hypovolemia
- absence of hypervolemia
- absence of signs of adrenal insufficiency or hypothyroidism
- nausea
- vomiting
- altered mental status
- headache
- seizure
- coma
Other diagnostic factors
- no history of recent diuretic use
Risk factors
- age >50 years
- pulmonary conditions (e.g., pneumonia)
- nursing home residence
- postoperative state
- malignancy
- medication associated with SIADH induction
- central nervous system (CNS) disorder
- endurance exercise
Diagnostic tests
1st tests to order
- serum sodium
- serum osmolality
- serum BUN
- urine osmolality
- urine sodium
Tests to consider
- diagnostic trial with normal saline infusion
- serum uric acid
- fractional excretion of sodium
- fractional excretion of urea
- serum TSH
- serum cortisol level
- serum arginine vasopressin (AVP)
Treatment algorithm
severe symptoms
mild to moderate symptoms
asymptomatic with sodium ≥125 mEq/L
persistence of chronic SIADH
Contributors
Authors
Megan Dixon, MD
Nephrologist
Arizona Kidney Disease and Hypertension Center
Phoenix
AZ
Disclosures
MD declares that she has no competing interests.
Yeonghau Howard Lien, MD, PhD
Professor Emeritus of Medicine
Division of Nephrology
University of Arizona
Tucson
AZ
Disclosures
YHL is an author of a reference cited in this topic.
Peer reviewers
Maryam Gondal, MD
Assistant Professor
Nephrology
Yale University
New Haven
CT
Disclosures
MG declares that she has no competing interests.
Judith H. Veis, MD
Associate Director
Nephrology
Washington Hospital Center
Washington
DC
Disclosures
JHV declares that she has no competing interests.
Laurie Solomon, MD, FRCP
Consultant Nephrologist
Renal Unit
Lancashire Teaching Hospitals
Fulwood
Preston
UK
Disclosures
LS declares that he has no competing interests.
References
Key articles
Gross P. Clinical management of SIADH. Ther Adv Endocrinol Metab. 2012 Apr;3(2):61-73.Full text Abstract
Spasovski G, Vanholder R, Allolio B, et al. Clinical practice guideline on diagnosis and treatment of hyponatraemia. Eur J Endocrinol. 2014 Mar;170(3):G1-47.Full text Abstract
Ball S, Barth J, Levy M, et al. Society for Endocrinology endocrine emergency guidance: emergency management of severe symptomatic hyponatraemia in adult patients. Endocr Connect. 2016 Sep;5(5):G4-6.Full text Abstract
Verbalis JG, Goldsmith SR, Greenberg A, et al. Diagnosis, evaluation, and treatment of hyponatremia: expert panel recommendations. Am J Med. 2013 Oct;126(10 suppl 1):S1-42.Full text Abstract
Ellison DH, Berl T. The syndrome of inappropriate antidiuresis. N Engl J Med. 2007 May 17;356(20):2064-72.
Reference articles
A full list of sources referenced in this topic is available to users with access to all of BMJ Best Practice.
Differentials
- Pseudohyponatremia
- Hypovolemia
- Cerebral salt-wasting
More DifferentialsGuidelines
- Emergency management of severe symptomatic hyponatraemia in adult patients
- Clinical practice guideline on diagnosis and treatment of hyponatraemia
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