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Opiates Screen, Urine
|Test Update Information||Effective 01/14/2013, the platform used for the opiate immunoassay screen has changed from the Abbot Axsym to the Beckman UniCel DxC 800. Additionally, the cutoff value to determine if a sample is positive has been reduced from 2000 µg/L to 300 µg/L, in line with best practice recommendations. This change will cause an approximately 17% increase in positive results in our patient population.
(Wu AHB et al, National Academy of Clinical Biochemistry Laboratory Medicine Practice Guidelines: Recommendations for the use of laboratory tests to support poisoned patients who present to the Emergency Department. Clin Chem, 2003, 49(3): 357-379)
|Performed by||Parnassus Chemistry|
|In House Availability||Test available 24 hours per day 7 days per week|
|Method||Competitive enzyme immunoassay method (Beckman UniCel DxC 800 analyzer) using G6PDH-labeling|
|Container type||Urine cup|
|Amount to Collect||See preferred volume|
|Sample type||Random urine|
|Preferred volume||1 mL urine|
|Min. Volume||0.5 mL urine|
Note: a negative result indicates that this class of drugs is not present, or they are present at a concentration below the cut-off concentration of 300 µg/L
|Stability||Refrigerated 7 days, frozen at -20C 2 weeks|
|Turn around times||Stat 2 hours, Routine 4 hours|
|Additional information||Morphine can be detected within 11-54 hours after use and can be detected as long as 11 days after use. (From: Verstraete AG. Detection Times of Drugs of Abuse in Blood, Urine and Oral Fluid. Ther Drug Monit, 26(2) April 2004, 200-205)
A concentration of < 300 µg/L is considered negative by this test. A positive result is ≥ 300 µg/L and indicates the presence of this class of drugs. This immunoassay is only a screening test and is not definitive. Results cannot be used for medico-legal purposes.
This is a presumptive screen for possible heroin or morphine use within the past 1-2 days. It may also detect morphine from the metabolism of codeine:
Click here for Opiate Metabolism Pathways
False positive results may occur due to other cross reacting substances, however, positive results are NOT routinely confirmed by a second method. If confirmation of the test result is required, it is the responsibility of the physician to separately order a specific confirmatory test for the drug identified. Samples are held for 7 days. Contact laboratory at x 31667 to request confirmatory testing. Confirmation test code OPIAC.
Click here for List of Cross Reactive Substances
The assay is not sensitive in detecting most prescribed opiates such as hydrocodone, hydromorphone, oxycodone and oxymorphone. A separate oxycodone screen is available at UCSF (test code: OXYU) that detects oxycodone and oxymorphone. If hydrocodone or hydromorphone use is suspected, an opiate confirmation should be ordered from Quest (test code: OPIAC). False negative results may also occur as use of synthetic and some semi-synthetic opiates cannot be ruled out by this assay. Specifically, this assay will not detect use of fentanyl, methadone, mepiridine or tramadol. If use of opiates not detected by this screen is suspected, immunoassay screens can be ordered from Quest [e.g. methandone (Quest#7176Z) and fentanyl (Quest#4175U)].
See also Drug Screening.
|Last Updated||1/15/2013 11:53:25 AM|
If you have additional questions regarding this test, please call: 415-353-1667