False-positive buprenorphine EIA urine toxicology results due to high dose morphine: A case report

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3 Scopus citations


In monitoring a patient with chronic pain who was taking high-dose morphine and oxycodone with weekly urine enzymatic immunoassay (EIA) toxicology testing, the authors noted consistent positives for buprenorphine. The patient was not taking buprenorphine, and gas chromatography/mass spectroscopy (GCMS) testing on multiple samples revealed no buprenorphine, indicating a case of false-positive buprenorphine EIAs in a high-dose opiate case. The authors discontinued oxycodone for a period of time and then discontinued morphine. Urine monitoring with EIAs and GCMS revealed false-positive buprenorphine EIAs, which remained only when the patient was taking morphine. When taking only oxycodone and no morphine, urine samples became buprenorphine negative. When morphine was reintroduced, false-positive buprenorphine results resumed. Medical practitioners should be aware that high-dose morphine (with morphine urine levels turning positive within the15,000 to 28,000 mg/mL range) may produce false-positive buprenorphine EIAs with standard urine EIA toxicology testing.

Original languageEnglish (US)
Pages (from-to)329-331
Number of pages3
JournalJournal of Addictive Diseases
Issue number4
StatePublished - Oct 1 2012


  • Buprenorphine
  • enzymatic immunoassay
  • false-positive buprenorphine
  • morphine
  • oxycodone

ASJC Scopus subject areas

  • Medicine (miscellaneous)
  • Clinical Psychology
  • Psychiatry and Mental health


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