American family physician
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American family physician · Mar 2010
Editorial CommentVitamin D in children: the right dose of evidence.
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Urine drug screening can enhance workplace safety, monitor medication compliance, and detect drug abuse. Ordering and interpreting these tests requires an understanding of testing modalities, detection times for specific drugs, and common explanations for false-positive and false-negative results. Employment screening, federal regulations, unusual patient behavior, and risk patterns may prompt urine drug screening. ⋯ Unexpected positive test results should be confirmed with gas chromatography/mass spectrometry or high-performance liquid chromatography. A positive test result reflects use of the drug within the previous one to three days, although marijuana can be detected in the system for a longer period of time. Careful attention to urine collection methods can identify some attempts by patients to produce false-negative test results.