Isotonic Water Overload

How to Cite This Chapter: Merali Z, Srivaratharajah K, Panju M, Mathew A, Kokot F, Franek E, Drabczyk R. Isotonic Water Overload. McMaster Textbook of Internal Medicine. Kraków: Medycyna Praktyczna. Accessed June 17, 2024.
Last Updated: January 18, 2022
Last Reviewed: January 18, 2022
Chapter Information

Definition, Etiology, PathogenesisTop

Isotonic water overload is characterized by an increase in the extracellular fluid (ECF), which manifests as edema. It is caused by increased sodium content in the body in the form of an isotonic solution. Sodium and water retention is mediated by hormonal factors (activation of the renin-angiotensin-aldosterone system; relative deficiency of natriuretic hormones, such as atrial natriuretic peptide) and nervous system factors (sympathetic activation).

Causes include heart failure, cirrhosis, nephrotic syndrome, and renal failure.

Clinical Features and DiagnosisTop

Signs, symptoms, and abnormalities in diagnostic studies depend on the underlying condition. Differential diagnosis of edema: see Edema.


1. Intensive treatment of the underlying condition.

2. Sodium and water restriction, administration of diuretics.Evidence 1Strong recommendation (benefits clearly outweigh downsides; right action for all or almost all patients). Moderate Quality of Evidence (moderate confidence that we know true effects of the intervention). Quality of Evidence lowered due to the risk of bias from the observational nature of supporting evidence. Yancy CW, Jessup M, Bozkurt B, et al. 2017 ACC/AHA/HFSA Focused Update of the 2013 ACCF/AHA Guideline for the Management of Heart Failure: A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines and the Heart Failure Society of America. J Card Fail. 2017 Aug;23(8):628-651. doi: 10.1016/j.cardfail.2017.04.014. Epub 2017 Apr 28. Review. PMID: 28461259.

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