MTLAWS Drug Testing Screening Laboratory Practice Test 2026 – Complete Exam Prep

The key idea is understanding that the screening cutoff is the concentration threshold used in the initial test to flag a specimen as presumptively positive for a drug. For methamphetamine, this threshold is 500 ng/mL. If a specimen is at or above this level, it triggers a confirmatory test (typically GC-MS) to verify and quantify the drug more accurately. This cutoff balances catching true positives with limiting false positives from cross-reacting substances or medications.

The other options aren’t appropriate because they either don’t represent a concentration threshold (one is a time frame, another uses a nonstandard unit), or they’re not expressed as the screening cutoff used in the initial immunoassay.