Describe the regulation of sodium in the body.
This question was generally poorly answered. Total body sodium is regulated within 2% in normal individuals. The vast majority is contained in the extracellular compartment. While any physiological regulation involves a balance of input and output, sodium intake is essentially unregulated in humans. Output is regulated via renal, gastrointestinal and skin losses. Candidates needed to present the renal handling of Na including hormonal control and present factual knowledge about the level of absorption and GFR effects to attain a pass mark. Many candidates focused on osmolality and tonicity and some on the use of diuretics thereby not gaining marks
on regulation of sodium. Most candidates didn’t mention either the skin and GIT role in sodium balance.
Distribution of sodium
Regulation of sodium intake
Regulation of intracellular/extracellular balance
Sodium sequestration in skin and connective tissue
Regulation of sodium and water elimination
Unregulated sources of sodium loss in the ICU
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