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Osmolality, serum

Item Value
Approval req'd? No
Available Stat? Yes
Test code OSM
Test group Osmolality
Performed by Parnassus & Mission Bay Chemistry
In House Availability Test available 24 hours per day 7 days per week
Method Freezing point depression
Container type Gold top or Light Green top
Amount to Collect 0.8 mL blood Click here for Microdetermination info
Sample type Serum
Preferred volume 0.4 mL serum
Min. Volume 0.1 mL serum Click here for Microdetermination info
Units mmol/kg (equiv. to mOsmol/Kg)
Normal range 283-301 mmol/kg
Critical value < 240 mmol/kg or > 320 mmol/kg
Synonyms volatiles; ethanol; etoh; ethylene glycol; methanol; alcohol
Stability Refrigerated 1 week
Turn around times STAT 1 hour, Routine same or next day
Additional information Each 0.10 g/dL of ethanol contributes about 22 mmol/kg to the endogenous osmolality of serum.

Predicted value = 2xNa [mmol/L] + Glucose [mg/dL]/18 + BUN [mg/dL]/2.8.

A measured value exceeding the predicted value by > 10 is consistent with, e.g., ethanol, methanol or ethylene glycol ingestion.

If specific testing for methanol, ethylene glycol and/or isopropanol is desired see entry for Drug screening - Volatiles
CPT coding 83930
LOINC code 2692-2
Last Updated 6/22/2016 12:39:44
Entry Number 698
Lab Procedure Link Click here for osmometer information
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