Amphetamine Detection Cutoff Concentrations on Urine Drug Screens
Standard immunoassay drug screens use a cutoff concentration of 500–1,000 ng/mL to detect amphetamine and methamphetamine, though many laboratories use 1,000 ng/mL as the reporting threshold, while MDMA detection often requires specific testing with lower cutoffs of 300–500 ng/mL. 1, 2, 3
Standard Screening Cutoffs
The most commonly used cutoff for amphetamine/methamphetamine immunoassay screening is 1,000 ng/mL, which is the standard threshold employed by most clinical laboratories for initial presumptive testing. 2
Some immunoassay platforms use a 500 ng/mL cutoff, and research demonstrates that this lower threshold can improve sensitivity for detecting amphetamine use while maintaining acceptable specificity. 2
A 300 ng/mL cutoff is used in some forensic and specialized clinical settings, particularly when higher sensitivity is required for detecting recent amphetamine exposure. 4
MDMA-Specific Considerations
MDMA (ecstasy) is often not detected by standard amphetamine panels, and specific testing for this substance may need to be requested separately, as standard drug testing panels are determined by local laboratory protocols and do not include many commonly abused substances. 1
Specialized MDMA immunoassays typically use cutoffs between 300–500 ng/mL to reliably detect methylenedioxymethamphetamine and related compounds. 3
The CEDIA Amphetamines/Ecstasy assay demonstrates superior performance for detecting MDMA at low concentrations compared to standard amphetamine panels, with the ability to predict MDMA concentrations more accurately than other immunoassay platforms. 3
Detection Performance by Cutoff Level
Using a 500 ng/mL screening cutoff results in sensitivity of 93–95% and specificity of 88–100% depending on the specific immunoassay platform employed, with optimal performance varying by manufacturer. 2
The optimal cutoff concentration varies between 271 ng/mL and 723 ng/mL across different immunoassay platforms when maximizing both sensitivity and specificity for amphetamine detection. 2
At concentrations below 150 ng/mL and above 1,000 ng/mL, immunoassay results show close agreement with confirmatory testing, but specimens with amphetamine concentrations between 300–1,000 ng/mL may produce false-negative results on some platforms. 4
Critical Clinical Caveats
Confirmatory Testing Requirements
All positive immunoassay results are presumptive only and require confirmation by gas chromatography-mass spectrometry (GC-MS) before making any consequential clinical decisions, as immunoassays are susceptible to cross-reactions with structurally similar compounds. 1, 5
Confirmatory testing by GC-MS typically uses a cutoff of 250 ng/mL for amphetamine, methamphetamine, MDMA, MDA, and MDEA to definitively identify the presence of these substances. 2, 6
False-Positive Considerations
Pseudoephedrine in over-the-counter cold medications is the most common cause of false-positive amphetamine results, producing positive immunoassay screens that require confirmatory testing to differentiate from actual amphetamine use. 1, 5
High concentrations of less reactive cross-immunoreactive compounds may mask low concentrations of actual amphetamines, limiting the positive predictive value of immunoassay screening when multiple sympathomimetic amines are present. 7
Detection Window
- Amphetamines can be reliably detected in urine for 48–72 hours after use using standard immunoassay screening with appropriate cutoff concentrations. 1
Laboratory-Specific Variations
Clinicians must contact their specific testing laboratory to understand which substances are included in their amphetamine panel and what cutoff concentrations are used, as these vary significantly between laboratories and testing platforms. 5
The Abuscreen OnLine HS Amphetamine/MDMA assay can detect both MDMA and methamphetamine at low concentrations, making it suitable for situations requiring enhanced sensitivity. 3
The Abbott FPIA (ADx platform) demonstrates 100% sensitivity with optimal specificity when using appropriate cutoff concentrations for amphetamine detection. 2