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