4 doctors weighed in:
What is plasma osmolarity? Plasma osmolality?
4 doctors weighed in

Dr. Joseph Woods
Pathology
2 doctors agree
In brief: Conc. electrolytes.
These refer to the concentration of electrolytes in the body/plasma, or the electrolyte-water balance.
These measure the same thing, only that osmolality is the number of osmoles per kilogram of solvent or osm/kg, while osmolarity is the number of osmoles per liter of solution or osm/ltr. Osmolality excludes the solute, while osmolarity includes it, so osmolality has a slightly higher reading.

In brief: Conc. electrolytes.
These refer to the concentration of electrolytes in the body/plasma, or the electrolyte-water balance.
These measure the same thing, only that osmolality is the number of osmoles per kilogram of solvent or osm/kg, while osmolarity is the number of osmoles per liter of solution or osm/ltr. Osmolality excludes the solute, while osmolarity includes it, so osmolality has a slightly higher reading.
Dr. Joseph Woods
Dr. Joseph Woods
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Dr. Gurmukh Singh
Pathology
1 doctor agrees
In brief: Minor difference
Osmolarity is number of moles in a liter of solution and osmolality is number of moles of solute in a kg of water. Normal plasma osmolality is about 290 mosmol/kg.

In brief: Minor difference
Osmolarity is number of moles in a liter of solution and osmolality is number of moles of solute in a kg of water. Normal plasma osmolality is about 290 mosmol/kg.
Dr. Gurmukh Singh
Dr. Gurmukh Singh
Thank
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