Osmolal or Osmolar Gap: Difference between revisions
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*[[Anion Gap (High)]] | *[[Anion Gap (High)]] | ||
*[[Toxidromes]] | *[[Toxidromes]] | ||
==External Links== | |||
*[http://www.mdcalc.com/serum-osmolality-osmolarity/ MDCalc - Serum Osmolality/Osmolarity] | |||
*[http://www.mdcalc.com/anion-gap/ MDCalc - Anion Gap] | |||
==References== | ==References== | ||
Revision as of 18:20, 19 February 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