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Urine drug testing

When to consider urine drug tests

Consider regular urine drug testing (UDT) for all patients on long-term opioid therapy (National Opioid Use Guideline Group ([NOUGG], 2010).

Urine drug tests can provide important clinical information:

  • The absence of a prescribed drug could indicate diversion or non-compliance.
  • The presence of an illegal drug could indicate a substance use problem.
  • The presence of a non-prescribed opioid could indicate double-doctoring or use of diverted opioids.

Types of urine drug testing

The two primary types of UDT are enzyme immunoassay and chromatography.

Table 1: Immunoassay versus chromatography for detection of opioid use

Table 2: Detection times for immunoassay and chromatography

Preparing for urine drug testing

Prior to the UDT, patients should provide a detailed history of their medication use over the preceding several hours and days. Ask, for example, whether patients took their opioid medication that morning.

Always inform patients that they are providing urine for UDT and obtain consent. UDT should be part of a treatment agreement.

Clinical experience demonstrates that patients will accept urine drug testing more readily if it is done routinely, not only when drug misuse is suspected.

Interpreting urine drug test results

Remember that UDT is just a lab test. Diagnoses and treatment decisions must be based on a careful assessment because a single UDT result can be misleading. An unexpected UDT result is not in itself sufficient to make a diagnosis of addiction. For example, the absence of a prescribed opioid does not necessarily mean that the patient is diverting the opioid. The result could be a false negative; the patient may have run out of the medication a few days before the test; or the patient may simply have been non-compliant and did not want to tell you.

Table 3: Interpreting unexpected results of urine drug screens suggests what to do when you receive an unexpected UDT result.