Typically, immunoassays for drugs o

Typically, immunoassays for drugs of abuse are thefirst line of testing for their ease of use, amenability toautomation, and rapid turnaround time. Invariably theseassays display some cross-reactivity with drugs from thesame class as well as with unrelated medications. Whileconfirmatory testing using mass spectrometry (GC-MSor LC-MS/MS) may be available, medical decisionmaking occurs before these results have returned. Another issue arises if confirmatory testing is simply notperformed. As with any medical test, proper interpretation should take into account known sensitivity and specificity issues to determine whether the results fit the clinical picture. In the context of PCP, some laboratorieshave chosen to remove PCP screening from their standard panels because false positives may outnumber confirmed positives (1). Even in facilities that perform PCPscreening, when confirmatory results are regularly negative, the ordering physicians may instinctively dismisspositive screening results. Given the proliferation ofnovel psychoactive substances (NPSs), any decision tonot test for PCP, not perform confirmatory testing, ornot trust a positive result must be done with careful consideration. Herein we have presented a case of 3-MeOPCP intoxication involving delirium with increased troponin I and CK that easily could have been attributederroneously to the patient’s prescription for tramadol, ifnot for the confirmatory testing.