A chronic pain patient receiving opioids should have appropriate drug testing to aid clinical management.
Patient selection: chronic pain patients receiving an opioid
Urine drug testing is used more often but serum or other body substances such as hair or saliva can be tested.
Indications for urine drug testing:
(1) when starting therapy with an opioid
(2) periodically during the course of therapy, at least once per year
(3) if opioid misuse or diversion is suspected
(4) to confirm compliance
(5) to detect abuse of other substances
Challenges in urine drug testing:
(1) specimen collection, to avoid substitution or adulteration
(2) false positive results (minimized if all positive results are confirmed by a specific assay)
(3) false negative results (reduced by ordering the appropriate test for the opioid being used and by testing to the limit of analysis)
For some drugs urine testing may be inadequate and serum testing is more appropriate.
Indications for serum drug testing:
(1) dose-related toxicity (accumulation, overdose, etc)
(2) to detect a drug with short half-life that may be missed by urine testing
(3) to troubleshoot issues related to drug kinetics
