Hypertonic Syndromes

Abstract

By definition hypertonicity reflects an increased concentration of nonpermeable solutes in plasma (P_osm > 300 mOsm/kg) which create an osmotic concentration gradient across the cell membrane and result in water moving out of cells. The number of solutes capable of causing hypertonicity is rather limited. Hypernatremia always represents hypertonicity, but all the other ions present in the extracellular fluid (potassium, magnesium, calcium) would cause specific lethal effects even before reaching concentrations sufficient to produce hypertonicity. From nonelectrolytes, only glucose and certain exogenous substances (as mannitol, sorbitol and glycerol when administered in sufficient amounts) can cause hypertonicity.