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Interpretive Handbook

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Test 8257:
Amphetamines, Urine

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

Amphetamines are sympathomimetic amines that stimulate the central nervous system activity and, in part, suppress the 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, attention-deficit disorder/attention-deficit hyperactivity disorder and minimal brain dysfunction.

 

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

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

Confirming drug exposure involving amphetamines such as amphetamine and methamphetamine, phentermine, methylenedioxyamphetamine (MDA), methylenedioxymethamphetamine (MDMA), and methylenediaoxyethylamphetamine (MDEA). MDA is a metabolite of MDMA and MDEA.

Interpretation Provides information to assist in interpretation of the test results

The presence of amphetamines in urine at concentrations >500 ng/mL is a strong indicator that the patient has used these drugs within the past 3 days.

 

This test will produce true-positive results for urine specimens collected from patients who are administered Adderall and Benzedrine (contain amphetamine); Desoxyn and Vicks Inhaler (contain methamphetamine); Selegiline (metabolized 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 detected 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

Positives are reported with a quantitative GC-MS result.

 

Cutoff concentrations:

IMMUNOASSAY SCREEN

<500 ng/mL

 

AMPHETAMINE BY GC-MS

<50 ng/mL

 

METHAMPHETAMINE BY GC-MS

<50 ng/mL

 

PHENTERMINE BY GC-MS

<50 ng/mL

 

METHYLENEDIOXYAMPHETAMINE BY GC-MS

<50 ng/mL

 

METHYLENEDIOXYMETHAMPHETAMINE BY GC-MS

<50 ng/mL

 

PSEUDOEPHEDRINE/EPHEDRINE (qualitative only)

<50 ng/mL reported as negative

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

1. Baselt RC: Disposition of Toxic Drugs and Chemicals in Man. Seventh edition. Foster City, CA. Biomedical Publications, 2004

2. Principles of Forensic Toxicology. Second edition, Washington, DC. AACC Press, 2003 pp 385