Osmolality: Difference between revisions
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==Values== | ==Values== | ||
*Calculated osmolarity = 2Na + Gluc/18 + BUN/2.8 | *Calculated osmolarity = '''2Na + Gluc/18 + BUN/2.8''' | ||
**Sodium multiplied by two to account for physiologic anions (chloride and bicarbonate) | **Sodium multiplied by two to account for physiologic anions (chloride and bicarbonate) | ||
**Na in mEq/L, Glucose in mg/dL, BUN in mg/dL | **Na in mEq/L, Glucose in mg/dL, BUN in mg/dL | ||
Revision as of 23:21, 18 February 2016
Background
- Primary determinants are sodium, glucose, BUN, chloride
- Osmolal gap
- When measured minus calculated > 10
- Suggests unmeasured, low molecular weight solutes
- EtOH
- Ethylene glycol
- Methanol
- Isopropyl alcohol toxicity
- Diethylene glycol
- Propylene glycol
- Mannitol
- Glycerol
- Smaller gaps possible in:
- Ketoacidosis
- Lactic acidosis
- Chronic kidney disease
Values
- Calculated osmolarity = 2Na + Gluc/18 + BUN/2.8
- Sodium multiplied by two to account for physiologic anions (chloride and bicarbonate)
- Na in mEq/L, Glucose in mg/dL, BUN in mg/dL
- Normal 280-295 mosmol/kg
Sources
- Emmett M et al. Serum osmolal gap. UpToDate. Aug 25, 2014. http://www.uptodate.com/contents/serum-osmolal-gap.