Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (1091 page)

   Screening

   Typically performed in urine

   Immunoassay-based technology performed on automated chemistry analyzers

   EIA (KIMS, CEDIA), EMIT, RIA, FPIA

   Qualitative

   Target: morphine, morphine–glucuronide

•   These “opiate” assays
do not detect
the semi/synthetic opioids, which include buprenorphine, methadone, meperidine, propoxyphene, nalbuphine, fentanyl, levorphanol, butorphanol, pentazocine, tapentadol, and tramadol.

•   These “opiate” assays have variable cross-reactivity with oxycodone, oxymorphone, hydrocodone, and hydromorphone.

•   Cutoff concentration—user defined.

○   300 ng/mL

○   2,000 ng/mL

   Specific immunoassays are available for individual synthetic compounds.

   
Oxycodone:
cutoff concentration 100 ng/mL; depending on the manufacturer, may exhibit approximately 100% cross-reactivity with oxymorphone

   
Methadone:
cutoff concentration 300 ng/mL; depending on the manufacturer, may exhibit approximately 40% cross-reactivity with methadol

   
Buprenorphine:
cutoff concentration 5 ng/mL; typically do not exhibit cross-reactivity with norbuprenorphine

   
Propoxyphene:
cutoff concentration 300 ng/mL; depending on the manufacturer, may exhibit approximately 60% cross-reactivity with norpropoxyphene

   Variable cross-reactivity with opioid metabolites