- New Urine Drugs of Abuse Test
On Wednesday, November 13, 2002, the clinical laboratories of the Department of Pathology will institute a new urine drugs of abuse test. Sample volume minimum is 10 mL (2mL for pediatrics). The new test differs from the current test in the following:
1. Alcohol is not included in the new screen. If alcohol intoxication is suspected a serum ethanol-volatiles screen should be ordered.
2. Amphetamine and methamphetamine will be reported as separate tests.
3. PCP and tricyclic antidepressants are included in the new screen. Presumably positive PCP samples will automatically be sent for confirmation. Presumably positive TCA samples will not automatically sent for confirmation. A tricyclic antidepressant screen performed on serum is available from the clinical laboratory.
4. The screen will be available 24 hours a day with a turnaround of 2 hours or less.
5. Threshold concentrations remain the same for most drugs. Barbiturates will go from 200 ng/mL to 300 and benzodiazepines will go from 100 ng/mL to 300. The threshold for PCP is 25 ng/mL and for TCA 1000 ng/mL.
This test provides only preliminary test results. Clinical consideration and professional judgment must be applied to any result, especially a presumptive positive. The test was designed to be used in patients attending a drug treatment program. The test was not designed as a toxicology screen and numerous articles have shown it to be of limited value in emergency situations. Cross-reacting drugs are listed in an appendix in the online laboratory handbook. Questions can be referred to Ronald Feld, Ph.D. (6-1759).
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