CPR’s “Coding Corner” focuses on coding, compliance and documentation issues relating specifically to physician billing. This month’s tip comes from G. John Verhovshek, the managing editor for AAPC, a training and credentialing association for the business side of health care.

CPT® provides three codes to describe qualitative drug testing (e.g., testing to determine if a particular analyte is present in the sample): 

• 80100 Drug screen, qualitative; multiple drug classes chromatographic method, each procedure


• 80101 single drug class method (eg, immunoassay, enzyme assay), each drug class


• 80104 multiple drug classes other than chromatographic method, each procedure

Chromatography, which involves passing a mixture that’s dissolved in a mobile phase through to a stationary phase to isolate molecules by type, is the most common method of drug screening. When using chromatography to identify multiple drug classes simultaneously, 80100 is appropriate.

Per CPT® instructions, you should count each combination of stationary and mobile phase as one procedure. “For example, if the detection of three drugs by chromatography requires one stationary phase with three mobile phases, use 80100 three times [once for each of the mobile phases]. However, if multiple drugs can be detected using a single analysis (e.g., one stationary phase with one mobile phase), use 80100 only once.”

In other words: When coding qualitative testing for multiple drug classes, determine how many mobile phases were done, and report 80100 that number of times.

When any method other than chromatography is used to identify multiple drug classes, you should report 80104. If qualitative methods other than chromatography are used to test for a single drug only, you should report 80101.

There has been great confusion on proper coding when using a “kit” containing multiple dipsticks (or cassettes, cups, etc.), each of which is used to detect a different analyte. AMA’s CPT Assistant, December 2010, explains, “Kits are commercially available for 12 or more analytes. These test kits are…effectively running multiple tests at once, in a single procedure, due to the test kit design.”

Proper coding when using such a “multiplex” test kit is a single unit of 80104 – not multiple units of 80101.

Prior to 2011, qualitative testing of multiple drug classes in a single kit commonly was reported using multiple units of 80101. CPT® 2011 changed this with the introduction of 80104, which was created specifically “to describe a non chromatographic method wherein multiple drug classes were screened in a single procedure…more accurately reflecting the resources used in a multiplex test kit as compared to multiple runs using a single class methodology,” according to CPT Assistant (Dec. 2010).

Be especially cautious that when reporting multiple units of 80101, you are certain each unit represents (and documentation substantiates) a unique test, rather than the individual components of a single multiplex testing kit. Improper coding results in grossly disproportional reimbursement and payers are actively targeting providers who report multiple units of 80101 in place of 80104 for multiplex drug test kits.

Finally, Medicare does not accept either 80100 or 80101. Instead, use G0431 Drug screen, qualitative; multiple drug classes by high complexity test method (eg, immunoassay, enzyme assay) per patient encounter and G0434 Drug screen, other than chromatographic; any number of drug classes, by CLIA waived test or moderate complexity test, per patient encounter. For additional instructions, see MLN Matters SE1105 Revised. Note that the Medicare codes specify “per patient encounter,” rather than per procedure or per analyte.