We have talked about initial screening tests and laboratory confirmatory tests, and that one of the differentiating characteristics between them is the sensitivity of the test. This feature refers to the ability of the test detect a drug in the sample (urine, blood or saliva). Thus, a “positive” or a “negative” result of the test is not absolute, but relative – if the concentration of a drug is below a certain cut-off level, the sample will be labeled “negative,” but this same sample can be read as “positive” if tested with a screen which cut-off level is lower. The tests with high cut-off levels are less sensitive, and the ones with lower cut-off levels are more sensitive and considered to be more accurate. You may wonder: what is the purpose of having tests with different sensitivity levels when you can do the same for everybody? Not only the price of the test is at issue, but also the fact that on a super-sensitive test with extremely low cut-off level it would be almost impossible to pass: a poppy-seed bagel would show up as opiate use, a simple aspirin or other NSAID will show marijuana exposure, diet pills… who knows what that will come up as! Sensitivity of a test would be indicated in the paperwork that you have to fill out before the actual test, so the cut-off levels would be stated there, but it does not hurt to mention everything that you take, even though it might be over-the-counter medicine, and everything that you ate in the past 24 hours before the test – you can never know what will come in handy when arguing the test results of a low cut-off level test.