ABSTRACT
The body of a person who weighs 70 kg contains approximately 42 litres of fluid. This consists of around 28 litres of intracellular fluid and 14 litres of extracellular fluid. The volume of the extracellular compartment is determined mainly by the total body sodium content, and to a lesser extent by the total body water content. The extracellular compartment consists of approximately 3 litres of plasma and 11 litres of interstitial fluid. This situation is maintained by two main mechanisms that act to keep fluid within the circulation. Hypoalbuminaemia of any cause will reduce the body's ability to hold fluid within the circulation, causing leakage into the interstitium. Disruption of the lymphatic system results in oedema by removing one of the main physiological mechanisms for returning interstitial fluid to the circulation.
