Pathology/Lab Coding Alert

Untangle multiple codes for single analyte.

With 10 new therapeutic drug assay codes and multiple drug testing guideline changes effective Jan. 1, we have the lowdown on how these updates can solve some vexing coding problems.

Read on to learn the about the new codes and the revisions that impact your lab.

Catch Up with These New Codes

According to CPT^® guidelines, tests in the CPT^® Therapeutic Drug Assay section serve the function of monitoring levels of known medications in the patient specimen such as blood (or components) or cerebrospinal fluid (CSF). Although the guidelines used to specify “prescribed” drugs, CPT^® 2021 adds “or over-the-counter” to the instructions, which accommodates new additions to the list such as acetaminophen and salicylate.

Here are the new codes, along with a note regarding drug class and common usage:

• 80143 (Acetaminophen) analgesic for pain or fever, over the counter (Tylenol)
• 80151 (Amiodarone) antiarrhythmic for irregular heartbeat
• 80161 (Carbamazepine; -10,11-epoxide) anticonvulsant for seizures: -10,11-epoxide monitors toxicity
• 80167 (Felbamate) anticonvulsant for seizures
• 80181 (Flecainide) antiarrhythmic for irregular heartbeat
• 80189 (Itraconazole) antifungal for infection
• 80193 (Leflunomide) disease-modifying antirheumatic drugs (DMARDs) for rheumatoid arthritis
• 80204 (Methotrexate) antimetabolites (slows cell proliferation), many cancers
• 80210 (Rufinamide) anticonvulsant for seizures
• 80179 (Salicylate) analgesic for pain or fever, over the counter (aspirin), nonsteroidal anti-inflammatory drug (NSAID)

Prior to the addition of these codes, therapeutic assays for many of these drugs had become more common, but specific CPT^® codes were lacking.

For instance: You now have a new code for therapeutic drug assay for Methotrexate (80204), which is an antimetabolite drug that may be used for autoimmune conditions such as rheumatoid arthritis (RA), and for chemotherapy for many types of cancer such as breast cancer, leukemia, lung cancer, and lymphoma. Having this new, specific therapeutic drug assay code should have a “big impact for oncology,” says Karen Pickering, RHIT, CCS, founder of ReviewMate and Senior Consultant for Pinnacle Enterprise Risk Consulting Services LLC.

Pitfall: Lacking a specific therapeutic drug assay code, the only appropriate code choice was 80299 (Quantitation of therapeutic drug, not elsewhere specified). However, “some labs were improperly reporting a definitive drug code, which pays many times the allowance for therapeutic drugs,” says William Dettwyler, MT-AMT, president of Codus Medicus, a laboratory coding consulting firm in Salem, Ore.

Guidelines Focus on Lab Method

Several drugs now have specific codes (either by name or by drug class) in more than one CPT^® drug-test section, such as in definitive drug testing, therapeutic drug assays, and chemistry sections.

For instance, you might report acetaminophen or salicylate using the new therapeutic drug assay codes 80143 and 80179 respectively, or using definitive drug test code 80329 (Analgesics, non-opioid; 1 or 2).

Basic: According to existing guidelines, therapeutic drug assays are used to monitor levels of a known medication, while definitive drug tests are used to identify and distinguish drugs and their metabolites in a specific drug class. But choosing the code based on the “purpose” may be confusing at times.

Problem: CPT^® also designates the lab methods represented by definitive drug test codes, such as liquid chromatography mass spectrometry (LC-MS), but specifies not to use the codes for immunoassay and enzymatic methods. This created a problem because many hospital labs (especially in rural areas) did not have this sort of complex instrumentation and, therefore, could not bill for the drugs listed in the definitive drug test section if they performed the test by immunoassay or enzymatic methods.

For example: A patient might come to the emergency room with a suspected acetaminophen overdose and need immediate lab results to determine treatment. “If the lab doesn’t have the complex instrumentation and performs a test such as a rapid enzymatic assay, they can’t bill 80329, but would need to bill 80299, or now, new code 80143,” Dettwyler says.

Look for Text Note Clarifications

CPT^® 2021 adds a series of text notes to help you choose the correct code based on lab method. These instructions will help you overcome the coding problem you may have faced when your lab test method doesn’t match the definitive drug codes.

Here are the CPT^® 2021 text notes that clarify how to choose the correct code for the following drugs:

Acetaminophen:

• Note under 80331: “For acetaminophen by immunoassay or enzymatic methods, use 80143.”
• Note under 80143: “For definitive drug testing for acetaminophen, see 80329, 80330, 80331.”

These notes were needed because the definitive drug definition excludes immunoassays, and the service can be performed by immunoassay, according to Lee Hillborne, MD, MPH, professor of pathology and laboratory medicine, UCLA school of medicine and senior medical director, medical affairs, Quest Diagnostics in his CPT^® and RBRVS 2021 Annual Symposium presentation.

Salicylate:

• Note under 80331: “For salicylate by immunoassay or enzymatic methods, use 80179.”
• Note under 80179: “For definitive drug testing for salicylate, see 80329, 80330, 80331.”
• Note in chemistry section in alphabetical order for aspirin: “For salicylate by immunoassay or enzymatic methods, use 80179.”
• Note in chemistry section in alphabetical order for salicylates: “For salicylate by immunoassay or enzymatic methods, use 80179.”

Alcohol: New code 82077 (Alcohol (ethanol); any specimen except urine and breath, immunoassay (eg, IA, EIA, ELISA, RIA, EMIT, FPIA) and enzymatic methods (eg, alcohol dehydrogenase))

• Note under 80320 (Alcohols): “For alcohol (ethanol) by immunoassay and enzymatic methods, use 82077.”
• Note under 82077: “For definitive drug testing for alcohol (ethanol), use 80320.”
• Note in chemistry section in alphabetical order for ethanol: “For definitive drug testing for alcohol (ethanol), use 80320).”
• Note in chemistry section in alphabetical order for ethanol: “For alcohol (ethanol) by immunoassay or enzymatic methods, use 82077.”