Drug screen - urine
No drugs in the urine.
If the test result is positive, it is helpful to confirm it with gas-chromatography mass spectrometry (GC-MS). In some cases, a test will register a false positive. This can result from interfering factors such as some foods, prescription medications, and other drugs.
The GC-MS will help tell the difference between a false positive or a true positive, resulting from the presence of an illegal drug.
McPherson RA, Pincus MR. Toxicology and therapeutic drug monitoring. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 21st ed. Philadelphia, Pa: Saunders Elsevier; 2006:chap 23.
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