Osmolal or Osmolar Gap: Difference between revisions

Revision as of 17:20, 21 February 2012

Calculated Osm = 2 x Na + (glu/18) + (BUN/2.8) + (ethanol/4.6) + (methanol/2.6) + (ethylene glycol/5) + (acetone/5.5) + (isopropanol/5.9)

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 ==Definitions==
-Osmolarity = the total number of particles in solution per liter
+*Osmolarity = the total number of particles in solution per liter
+*Osmolality = the number of particles per kilogram of solvent
-Osmolality = the number of particles per kilogram of solvent
-==Background==
-Serum osmolality should be measured by the freezing-point depression method rather than by the vapor pressure method, since the latter technique will underestimate the concentrations of volatile alcohols (methanol, ethylene glycol, and isopropanol).
 ==Calculations==
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 ===Osmolal Gap===
+*Osmolal Gap = measured osm - calculated osm
-Osmolal Gap = measured osm - calculated osm
+**Normal = (-)14-10 mOsm/L
-(Normal = (-)14-10 mOsm/L)
 ==DDX==
-===Increased)===
 #Alcohols
-##methanol
+##Methanol
-##ethylene glycol
+##Ethylene glycol
-##isopropanol
+##Isopropyl
 #Sugar
-##glycerol
+##Glycerol
-##manitol
+##Manitol
 #Ketones
-##acetone
+##Acetone
 ==See Also==
-[[Anion Gap and Osmolar Gap (High)]]
+*[[Anion Gap and Osmolar Gap (High)]]
 [[Category:FEN]]
 [[Category:Tox]]