Clinical Textbook of Addictive Disorders 3rd ed - R. Frances, S. Miller, A. Mack (Guilford, 2005) WW

64 II. ASSESSMENT OF ADDICTION1. For what drugs ought we to test?2. What biological sample should be tested: urine, blood, sweat, saliva,hair, and so forth?3. How fast do we want to see the results?4. How much of our resources should be spent on testing?This chapter reviews testing methodologies and the fundamental aspects ofplanning effective testing procedures in both clinical and consultative settings.TESTING METHODOLOGIESA multitude of methods are available to aid in the detection of drug use inhumans. The most common drug testing technologies are listed in Table 4.1.The most popular initial test screen is an enzyme immunoassay (EIA) analysisof a urine sample. If this is positive, a confirmatory gas chromatography–massspectroscopy (GC-MS) test is performed on the split sample. Given the greatersensitivity of GC-MS over EIA, the cutoff levels are reduced. The most commonlyused analytic technique for a “comprehensive drug screen,” thin-layerchromatography (TLC), is the least expensive test available. TLC utilizes thedifferences in polarity and chemical interaction with developing solvents toproduce different visualizations on a thin-layer coating. The visualizations arehighlighted using ultraviolet (UV) or fluorescent lighting, or by color reactionscreated after being sprayed with chemical dyes. Identical molecules cluster inthe same area, yielding specific color reactions. Unfortunately, TLC is somewhatinsensitive to detection of controlled substances.Of all the available tests, how does a clinician decide on which test toadminister? If there is no clinical indication to test for a specific compound,a “comprehensive drug screen” may be performed. There are settings andinstances when it is important to contact the laboratory to ensure that there is ameans to test for the substance, or to prompt the laboratory to test for the sub-TABLE 4.1. Most Common Drug Testing Technologies• Thin-layer chromatography• Radio immunoassay, enzyme immunoassay, fluorescentpolarization immunoassay, enzyme-linked immunosorbent assay• Gas chromatography• Gas chromatography–mass spetroscopy• Liquid chromatography