There are two main categories of urine drug testing – screening (aka presumptive) followed by confirmation (CMS, 2016). Screening tests are initial, qualitative drug tests conducted to identify classes of drugs present in the urine and typically are done using immunoassay. They rely on a set threshold above which a positive result is produced and therefore do not detect lower concentrations of a drug.

Confirmatory tests are used for further analysis of a sample – to confirm a positive or sometimes, negative, result and typically are done using gas chromatography/mass spectometry (GC/MS) or high-performance
liquid chromatography (HPLC). Confirmatory testing can identify a specific
drug. If the goal is to detect a synthetic or semi-synthetic opioid, this testing should be used as immunoassays do not typically detect these opioids.

Note that requirements for testing vary with the health insurance, with respect to
reimbursement for UDT. For example, requirements have been shifting for Medicare and will likely continue to shift (CMS, 2016). For example, insurance may vary as to which codes they will reimburse; some may not reimburse multiple individual substances. Therefore, we recommend that providers consult with the insurance company in question before ordering drug tests.

Below is a comparison of the general characteristics of these two types of testing:

More Details can be found at

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