Pathology/Lab Coding Alert

Question: If a physician orders total T4 and TSH tests for a patient with hypothyroidism following thyroid cancer surgery and postsurgical radiation therapy, should we code a thyroid function panel and 244.9 for the diagnosis?

North Carolina Subscriber

Answer: The correct coding for this case is 84436 (Thyroxine; total) plus 84443 (Thyroid stimulating hormone [TSH]) for the tests, and 244.1 (Acquired hypothyroidism, other postablative hypothyroidism) for the diagnosis.

CPT doesn't provide a "thyroid panel" code, so you need to report the ordered tests individually using 84436 and 84443. Physicians often order total thyroxine as total T4 or TT4. Your diagnosis coding should be more precise for this patient, because 244.9 (Unspecified hypothyroidism) does not reflect the postsurgical/post-radiation state of the patient's condition. When the patient has recently had thyroid surgery or radiation therapy that caused the hypothyroidism, choose the fourth digit based on the most recent factor influencing the hypothyroidism.

If the patient most recently had surgery, report 244.0 (Postsurgical hypothyroidism). If the radiation therapy was more recent, report 244.1.

Medicare's laboratory National Coverage Determination (NCD) for thyroid testing provides the following frequency restrictions for thyroid tests: "Testing may be covered up to two times a year in clinically stable patients; more frequent testing may be reasonable and necessary for patients whose thyroid therapy has been altered or in whom symptoms or signs of hyperthyroidism or hypothyroidism are noted."

That means if the patient has had more frequent TT4 or TSH tests, the physician should provide the lab with other diagnostic information such as symptoms or medication data. That way, the lab can use an additional diagnosis code such as V58.69 (Long term [current] use of other medications).

You'll need the extra diagnosis to get paid for more frequent thyroid tests, because the lab NCD states, "When these tests are billed at a greater frequency than the norm (two per year), the ordering physician's documentation must support the medical necessity of this frequency."