Osmolality: Difference between revisions

Revision as of 23:23, 18 February 2016

Primary determinants are sodium, glucose, BUN, chloride
Osmolal gap
- When measured minus calculated > 10
- Suggests unmeasured, low molecular weight solutes

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

Emmett M et al. Serum osmolal gap. UpToDate. Aug 25, 2014. http://www.uptodate.com/contents/serum-osmolal-gap.

Authors:

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 ==Background==
+===Osmolar Gap===
 *Primary determinants are sodium, glucose, BUN, chloride
 *Osmolal gap
 **When measured minus calculated > 10
 **Suggests unmeasured, low molecular weight solutes
-***EtOH
+====Values====
-***[[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
+====DDx====
+*EtOH
+*[[Ethylene glycol]]
+*[[Methanol]]
+*[[Isopropyl alcohol toxicity]]
+*[[Diethylene glycol]]
+*[[Propylene glycol]]
+*[[Mannitol]]
+*Glycerol
+*Smaller gaps possible in:
+**Ketoacidosis
+**[[Lactic acidosis]]
+**[[Chronic kidney disease]]
 ==Sources==