Plasma Osmolality
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We calculate plasma osmolality to measure the body's electrolyte-water balance.
Plasma Osmolality =osmol/kgH2O
= 2 * [Na+] [mEq/L] + Glucose (mg/dL)/18 + BUN (mg/dL)/2.8
- * Osmolality vs Osmolarity:
- Osmolality = the number of osmoles (Osm) of solute per kilogram of solvent (osmol/kg or Osm/kg)
- Independent of temperature and pressure
- Osmolarity = the number of osmoles of solute per liter (L) of solution (osmol/L or Osm/L).
- Affected by changes in water content, temperature and pressure