Volume vs water balance

Q: Serum sodium concentration represents? (select one)

A) volume balance

B) water balance

Answer: B

This question's objective is to highlight that water balance and volume balance are two different entities. Serum sodium level provides information only on total body water balance. Other clinical and laboratory factors should be considered to determine total body volume balance. Merely looking at serum sodium concentration does not determine 'dry' vs. 'wet' status. Water deficit is a complex phenomenon and rarely occurs acutely in the human body unless there is a reason to believe in any accelerated water losses.

#electrolytes

Reference:

Sterns RH, Silver SM. Salt and water: read the package insert. QJM 2003; 96:549.