Internal Medicine Coding Alert

Question: We have a patient that comes into the office and requires anticoagulant management and is taking warfarin. Should I be using 99363 or 99364?

Nebraska Subscriber

Answer: You would use 99363 (Anticoagulant management for an outpatient taking warfarin, physician review and interpretation of International Normalized Ratio [INR] testing, patient instructions, dosage adjustment [as needed], and ordering of additional tests; initial 90 days of therapy [must include a minimum of 8 INR measurements]) during the initial 90 days of treatment and 99364 (Anticoagulant management for an outpatient taking warfarin, physician review and interpretation of International Normalized Ratio [INR] testing, patient instructions, dosage adjustment [as needed], and ordering of additional tests; each subsequent 90 days of therapy [must include a minimum of 3 INR measurements]) during each subsequent 90 days of therapy following the initial treatment.

Your physician should be looking after the patient on an outpatient basis. To bill this service, she needs to take at least 3 measurements using prothrombin time tests. During the 90 days, she will access the patient’s medical record, review the results, and make changes in doses if she sees any specific patterns in the test study.

The treatment plan may also be changed in the case of any acute illness or possible drug interactions. Specific dietary instructions may be needed regarding the foods affecting vitamin K levels and/or procedures that require withholding or alternative anticoagulation. You’ll use 99363-99364 to cover these services, too, as they are not separately reportable. 

In addition, your physician will most likely make a notation in the medical record, contact the patient to inform him about the results and instructions, and arrange for repeat testing at the appropriate interval.

Note: Medicare and some private payers do not cover these codes, so check with your payer before reporting 99363-99364.