ICD 10 Coding Alert

Looking at the order can provide helpful context.

If you work at a lab and receive a request for drug testing, you may be able to glean from the order whether the test was ordered for screening or diagnostic purposes.

Find out which ICD-10-CM code represents a clinical situation involving a chemotherapeutic agent.

Clinical example: The clinician orders a test for the serum level of methotrexate, a specific chemotherapeutic agent, for a patient complaining of vomiting and throat pain following a recent chemotherapy infusion that was administered per the physician’s order.

Become Familiar With Drug Toxicity Classifications

Codes in categories T36-T65 are combination codes that identify the substance the patient took as well as the intent. The Table of Drugs and Chemicals pinpoints the correct code for a specific type of drug and a specific type of toxicity.

To know why a clinician is ordering a specific diagnostic drug test, you need to understand the types of drug toxicity represented in ICD-10:

• Adverse effect: Problem that arises after taking a drug that has been correctly prescribed and properly administered
• Poisoning: Reaction to the improper use of a medication
• Underdosing: Taking less of a medication than is prescribed
• Toxic effect: Ingestion or contact with a harmful substance

“The key to coding from the Table of Drugs and Chemicals in ICD-10-CM is understanding the differences between these definitions, knowing the difference between adverse effect, poisoning, underdosing, and toxic effect,” says Barbara J. Cobuzzi, MBA, CPC, COC, CPC-P, CPC-I, CENTC, CPCO, CMCS, of CRN Healthcare in Tinton Falls, New Jersey.

Remember to Consider a Z Code

The 2023 ICD-10-CM code set expands your options in category Z79- (Long term (current) drug therapy). This code boost allows clinicians to identify the type of chemotherapy being administered to the patient. If the specific drug is documented, the clinician should now assign one of the following codes from the Z79.63- (Long term (current) use of chemotherapeutic agent) group:

• Z79.630 (Long term (current) use of alkylating agent) for chlorambucil, cisplatin, and cyclophosphamide
• Z79.631 (Long term (current) use of antimetabolite agent) for methotrexate, 5-fluorouracil, 6-mercaptopurine, and cytarabine
• Z79.632 (Long term (current) use of antitumor antibiotic) for bleomycin, doxorubicin, and mitomycin C
• Z79.633 (Long term (current) use of mitotic inhibitor) for paclitaxel, plant alkaloids, vinblastine, and vincristine
• Z79.634 (Long term (current) use of topoisomerase inhibitor) for etoposide, irinotecan, and topotecan

Note: Be on the lookout for when the Centers for Medicare & Medicaid Services (CMS) adds the Z79.63- codes to the National Coverage Determination (NCD) and Local Coverage Determination (LCD) lists and articles. “Ordering lab work to monitor patients on these newly represented medications may not be covered if reported with Z79.899 [Other long term (current) drug therapy],” cautions Halee Garner, CPC, CPMA, CCA, certified coder for Digestive Health Partners in Asheville, North Carolina.

Procedure: With a request for methotrexate serum level for a patient with Z79.631 and T45.1X (Poisoning by, adverse effect of and underdosing of antineoplastic and immunosuppressive drugs) ordering diagnoses, the lab should perform a therapeutic drug assay test, not a screening drug test, and report the service as 80204 (Methotrexate).