Summary
Definition
History and exam
Key diagnostic factors
- presence of risk factors
- high fluid intake
- fluid losses
- history of diabetes mellitus
- history of cirrhosis, nephrosis, congestive heart failure
- nausea/vomiting
- mild cognitive symptoms
- altered mental status, seizures, coma
- low urine output
- weight changes
- orthostatic hypotension
- abnormal jugular venous pressure
- poor skin turgor
- dry mucous membranes
- absence of axillary sweat
- oedema
- rales or crackles on lung auscultation
- polyuria
Risk factors
- older age
- hospitalisation
- selective serotonin-reuptake inhibitor (SSRI) use
- thiazide diuretic use
- underlying medical conditions
- severe hypothyroidism
- adrenal insufficiency
- malignancy
- use of other medications
- MDMA (ecstasy) use
Diagnostic investigations
1st investigations to order
- serum sodium concentration
- serum electrolytes, urea, creatinine, and glucose
- serum osmolality
- urine sodium concentration
- urine osmolality
- urine electrolytes
- urine flow rate
- electrolyte-free water excretion
- fractional excretion of sodium
- thyroid-stimulating hormone
- serum cortisol level and/or adrenocorticotrophic hormone test
- serum lipids and serum protein electrophoresis
Investigations to consider
- CT brain, chest, abdomen/pelvis
- other tests targeted at evaluating the underlying cause
Treatment algorithm
Contributors
Authors
Judith H. Veis, MD
Section Director
Nephrology
MedStar Washington Hospital Center
Washington
DC
Disclosures
JHV declares that she has no competing interests.
Peer reviewers
Gregor Lindner, MD
Director
Department of Internal & Emergency Medicine
Hirslanden Klinik Im Park
Zurich
Switzerland
Disclosures
GL is an author of a number of references cited in this topic.
Michael E. Ullian, MD
Professor of Medicine
Division of Nephrology
Department of Medicine
Medical University of South Carolina
Charleston
SC
Disclosures
MEU declares that he has no competing interests.
References
Key articles
Spasovski G, Vanholder R, Allolio B, et al; Hyponatraemia Guideline Development Group. Clinical practice guideline on diagnosis and treatment of hyponatraemia. Eur J Endocrinol. 2014 Feb 25;170(3):G1-47.Full text Abstract
Adrogué HJ, Tucker BM, Madias NE. Diagnosis and management of hyponatremia: a review. JAMA. 2022 Jul 19;328(3):280-91. Abstract
Verbalis JG, Grossman A, Höybye C, et al. Review and analysis of differing regulatory indications and expert panel guidelines for the treatment of hyponatremia. Curr Med Res Opin. 2014 Jul;30(7):1201-7. Abstract
Hoorn EJ, Zietse R. Diagnosis and treatment of hyponatremia: compilation of the guidelines. J Am Soc Nephrol. 2017 May;28(5):1340-9.Full text Abstract
Reference articles
A full list of sources referenced in this topic is available here.
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