Question: We frequently get patients coming in for a Protime test with a diagnosis of ""Coumadin therapy."" Which ICD-9 code should I use to report this? I've been told that I need to code the reason that the patient is on Coumadin therapy.
Answer: If the patient is having a Protime test (85610, Prothrombin time) to monitor Coumadin therapy, you should report V58.83 (Encounter for therapeutic drug monitoring). A note under the code states, ""Use additional code for any associated long-term (current) drug use (V58.61-V58.69)."" In this case, Coumadin is an anticoagulant, so you should report V58.61 (Long-term [current] use of anticoagulants) in addition to V58.83.
Medicare's National Coverage Determination for Prothrombin time lists V58.61 as a payable diagnosis for 85610. You may also code the underlying condition as a secondary diagnosis if provided by the ordering physician, although it is not necessary. For example, if the physician order states that the patient has atrial fibrillation, you can report 427.31 (Atrial fibrillation) as the secondary diagnosis.