Electrolyte Balance · Physiology

The primary extracellular cation responsible for determining plasma osmolality is:

  1. Potassium
  2. Calcium
  3. Sodium
  4. Magnesium
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Correct answer: Sodium

Sodium is the major extracellular cation and the main determinant of plasma osmolality. Changes in sodium concentration strongly influence water balance.

Difficulty: Medium Question 1 of 20

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