Body fluid compartments, Starling forces and the distribution of intravenous fluids
The sizes of total body water and its compartments, how osmolality moves water between them, where 1 L of dextrose, saline or albumin ends up, and the revised Starling principle behind oedema.
Tier 2Medical sciences concept
Written with AI assistance and fact-checked against the sources below. For exam study, not clinical decisions. How notes are made
At a glance
- Total body water (TBW) is about 60% of body weight in young men, 50% in women and older men, and 45% in older women.
- Two-thirds ICF, one-third ECF. The ECF splits about three-quarters interstitial and one-quarter plasma.
- Water moves between ICF and ECF by osmosis. Sodium (ECF) and potassium (ICF) are the effective osmoles that hold each compartment's water.
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Sources
- Guyton and Hall Textbook of Medical Physiology (14th ed.)Elsevier (Hall and Hall, 2021), 2021
- Woodcock TE, Woodcock TM. Revised Starling equation and the glycocalyx model of transvascular fluid exchange: an improved paradigm for prescribing intravenous fluid therapy. Br J Anaesth 2012;108(3):384-94British Journal of Anaesthesia, 2012
- Finfer S et al. A comparison of albumin and saline for fluid resuscitation in the intensive care unit (SAFE). N Engl J Med 2004;350:2247-56New England Journal of Medicine, 2004
- Finfer S et al. Balanced multielectrolyte solution versus saline in critically ill adults (PLUS). N Engl J Med 2022;386:815-26New England Journal of Medicine, 2022
- Therapeutic Guidelines: Kidney and UrinaryAU/NZTherapeutic Guidelines Limited, 2026
- Last updated
- 14 November 2026
What changed
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