OSMOLALITY, serum or plasma (087-0333)
Synonyms: OSMO
CPT 4 Code: 83930
Test Order Mnemonic: OSMO
Lab: Clinical Chemistry
Request Form: Routine Chemistry Form 1
Collection: Routine venipuncture
Storage Instructions: Centrifuge the specimen, separate serum
from cells within 2 hours of collection and refrigerate.
Causes for Rejection: Gross hemolysis
Availability: Samples are accepted 24 hours per day at Sample
Management, 5.136 McCullough.
Turnaround Time: Routine: 4 hours; STAT: 1 hour
Specimen: Blood
Volume: 1 mL blood if heparinized; 2 mL blood if not
anticoagulated
Container: Heparinized syringe or green-topped (heparin)
vacutainer tube for plasma; red-topped tube for serum
Reference Ranges: 285-295 mOsm/kg
Critical Values: <240 mOsm/kg or >320 mOsm/kg
Test Method: Freezing Point Depression
Reviewed/revised April 2007 by P. Harris
