You might need to pre-empt Category I. There’s a catch for all the drug-test coding advice you read about in the preceding article. “If your lab performs a proprietary laboratory analysis (PLA) test, you must use the appropriate PLA code instead of a Category I code,” explains William Dettwyler, MT AMT, president of Codus Medicus, a laboratory coding consulting firm in Salem, Ore. Terminology: A PLA code describes a clinical lab test that only a single lab performs, or a test from a specific manufacturer. The following table shows current PLA drug test codes that you should know.