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Interpretive Handbook

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Test 505341:
Drug of Abuse, Amphetamine Screen with GC-MS Confirmation, Urine

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

Amphetamines are sympathomimetic amines that stimulate central nervous system activity and, in part, suppress appetite. Phentermine, amphetamine, and methamphetamine are prescription drugs for weight loss. All of the other amphetamines are Class I (distribution prohibited) compounds. In addition to their medical use as anorectic drugs, they are used in the treatment of narcolepsy and minimal brain dysfunction.

 

Because of their stimulant effects, the drugs are commonly sold illicitly and abused. Physiological symptoms associated with amphetamine overdose include elevated blood pressure, dilated pupils, hyperthermia, convulsions and acute psychosis.

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

Confirming drug abuse involving amphetamines such as amphetamine and methamphetamine, phentermine, methylenediaoxyethylamphetamine (MDEA), and methylene-diaoxyethylamphetamine (MDA, a metabolite of MDMA and MDEA)

Interpretation Provides information to assist in interpretation of the test results

The presence of amphetamines in urine concentrations >499 ng/mL is a strong indicator that the patient has used 1 of these drugs within the past 3 days. This test is very specific and does not produce a false-positive result when over-the-counter drugs are present in the specimen. This test will produce true-positive results for urine specimens collected from patients who are administered Adderall and Benzedrine (which contain amphetamine); Desoxyn and Vicks Inhaler (which contain methamphetamine); Selegiline (metabolizes to methamphetamine and amphetamine); and clobenzorex, famprofazone, fenethylline, fenproporex, and mefenorex (which are amphetamine pro-drugs).

Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

Over-the-counter sympathomimetics such as ephedrine and phenylpropanolamine are occasionally confused as amphetamines in the screening immunoassay.

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: 500 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