Pathology/Lab Coding Alert

Question: When the lab performs tests for medication monitoring, what ICD-9 codes should we report?

Minnesota Subscriber

Answer: You should report the diagnosis that the ordering physician provides as the reason for the test. If the patient has no symptoms and the physician orders the test simply to monitor the medication's effects, you should use a code from subcategory V58.6x (Long-term [current] drug use).

For instance: If the physician orders prothrombin time (PTT) to monitor the Coumadin's blood-thinning effects, you should list V58.61 (Long term [current] use of anticoagulants) as the ordering diagnosis for 85730 (Thromboplastin time, partial [PTT]; plasma or whole blood).

Caution: Do not assign a code from subcategory V58.6x for medication that a physician administers for a brief time period to treat an acute illness or injury (such as a course of antibiotics to treat acute bronchitis).

If the physician orders a test based on patient symptoms that may be caused by a medication, you should report the symptoms in addition to V58.6x. For example, if the physician orders a blood test because the patient suddenly starts to have joint pain, report a code from the 719.4x series (Pain in joint) as the ordering diagnosis.