Osmolal or Osmolar Gap: Difference between revisions
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===Osmolal Gap=== | ===Osmolal Gap=== | ||
Osmolal Gap = measured osm - calculated osm | Osmolal Gap = measured osm - calculated osm | ||
*Normal = | *Normal = +/- 14-10 mOsm/L | ||
==Differential Diagnosis== | ==Differential Diagnosis== | ||
Revision as of 15:53, 22 July 2016
Definitions
- Osmolarity = the total number of particles in solution per liter
- Osmolality = the number of particles per kilogram of solvent
Calculations
Calculated Osm
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)
- Normal = 275-295
Osmolal Gap
Osmolal Gap = measured osm - calculated osm
- Normal = +/- 14-10 mOsm/L
Differential Diagnosis
- EtOH
- Ethylene glycol
- Methanol
- Isopropyl alcohol toxicity
- Diethylene glycol
- Propylene glycol
- Mannitol
- Glycerol
- Smaller gaps possible in:
- Ketoacidosis
- Lactic acidosis
- Chronic kidney disease