Pathology/Lab Coding Alert

Question: How should we bill for INR testing at our Coumadin Clinic, including how to report services when the pathologist or other healthcare provider manages patient dosing based on lab or home monitoring results?

Indiana Subscriber

Answer: International Normalized Ratio (INR) is a calculated value based on the results of a prothrombin time (PT) lab test. If your Coumadin clinic lab performs the test, report the service as 85610 (Prothrombin time). The test involves mixing patient blood with reagents and noting the time (in seconds) that it takes for the blood to clot. Labs express PT test results (clotting time) in seconds and/or as an INR number. The clotting time indicates the effectiveness of the medication at the current dosage.

INR: Commercial thromboplastin reagents used in laboratory PT tests have different potencies, so the INR reporting method “normalizes” results by reporting the PT ratio that would result if the World Health Organization reference thromboplastin were used to perform the test.

Monitoring, management: In addition to the lab test, you might bill one of the following codes if your pathologist or other qualified healthcare professional performs these services as part of patient management in a setting such as a Coumadin clinic:

• 93792 (Patient/caregiver training for initiation of home international normalized ratio [INR] monitoring under the direction of a physician or other qualified health care professional ...)
• 93793 (Anticoagulant management for a patient taking warfarin, must include review and interpretation of a new home, office, or lab international normalized ratio (INR) test result, patient instructions, dosage adjustment (as needed), and scheduling of additional test(s), when performed)

For similar services for Medicare beneficiaries, remember that you have the following three existing codes to choose from:

• G0248 (Demonstration, prior to initiation of home INR monitoring, for patient with either mechanical heart valve[s], chronic atrial fibrillation, or venous thromboembolism who meets Medicare coverage criteria, under the direction of a physician; includes: face-to-face demonstration of use and care of the INR monitor, obtaining at least one blood sample, provision of instructions for reporting home INR test results, and documentation of patient’s ability to perform testing and report results)
• G0249 (Provision of test materials and equipment for home INR monitoring of patient with either mechanical heart valve[s], chronic atrial fibrillation, or venous thromboembolism who meets Medicare coverage criteria; includes: provision of materials for use in the home and reporting of test results to physician; testing not occurring more frequently than once a week; testing materials, billing units of service include 4 tests)
• G0250 (Physician review, interpretation, and patient management of home INR testing for patient with either mechanical heart valve[s], chronic atrial fibrillation, or venous thromboembolism who meets Medicare coverage criteria; testing not occurring more frequently than once a week; billing units of service include 4 tests)

Bottom line: Because PT is such a common test for monitoring warfarin therapy, as well as for other medical indications, many payers have policies concerning coverage rules, testing frequency, coding requirements, and more that you should be aware of.