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Interpretive Handbook

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Test 505230:
Drug of Abuse, Cocaine Screen with GC-MS Confirmation, Urine

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Cocaine, a central nervous system stimulant, is a drug of current health concern because of its proliferation among recreational drug abusers. Cocaine can be taken in a variety of ways. It can be inhaled, injected intravenously, or the base can be smoked (crack). Freebase and crack increase the potential for major toxicity. Increasingly, laboratory results are disputed or there are medical/legal overtones. Therefore, physicians are finding an increased need to confirm positive results before informing or confronting the patients.

 

Cocaine is almost completely metabolized by the liver, with only about 1% being excreted unchanged. The rate of excretion depends on the individual and the mode of administration. Benzoylecgonine is the major metabolite, but some is excreted as ecgonine methyl ester and ecgonine. Benzoylecgonine can be detected in urine within 4 hours following inhalation and can remain detectable for as long as 48 hours.

Useful For Suggests clinical disorders or settings where the test may be helpful

Detecting drug abuse involving cocaine

Interpretation Provides information to assist in interpretation of the test results

The presence of cocaine, or its major metabolite, benzoylecgonine indicates use within the past 4 days.

 

Cocaine has a 6-hour half-life, so it will be present in urine for 1 day after last use.

 

Benzoylecgonine has a half-life of 12 hours, so it will be detected in urine up to 4 days after last use.

Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

Negative

EMIT cutoff concentration: 150 ng/mL

Positives are reported with a quantitative GC-MS result.

Clinical References Provides recommendations for further in-depth reading of a clinical nature

Baselt RC, Cravey RH: Disposition of Toxic Drugs and Chemicals in Man. Third edition. Chicago, Year Book Medical Publishers, 1989