Specimen Requirements



Specimen Requirement

Collect red top or lavender (EDTA), send 0.25 mL serum/plasma. Centrifuge, separate serum/plasma within two hours of collection, transfer to a screw top transport tube, indicate sample type on tube and send.

Alternate sample: Green top heparin

The use of gel-barrier tubes is not recommended due to slow absorption of the drug by the gel. Depending on the specimen volume and storage time, the decrease in drug level due to absorption may be clinically significant.


Liquid chromatography/tandem mass spectrometry (LC/MS-MS)


Room temp: 14 days, Refrigerated: 14 days, Frozen: 14 days

Reference Range

By Report*


3-7 days

Clinical Use

Relief of moderate to moderately-severe pain. Indications for monitoring include the following: to confirm or identify suspected drug toxicity in chronic use, therapeutic misadventure, or accidental or intentional acute overdose; to aid in the identification of an unknown drug ingested in unknown quantities, drug identification and/or quantitation may be performed as an adjunct for patient management; to monitor selected patient groups at greater risk for analgesic drug toxicity or drug-to-drug interaction; to confirm complete drug absorption and adequate drug elimination as an adjunct to overdose management.

Test Code