Pathology/Lab Coding Alert

Question: Our lab recently began performing the free T4 thyroid test. Previously, we performed only the total thyroxine and T3 uptake tests. Now some physicians are ordering all three tests to evaluate thyroid function, but we've been getting Medicare denials stating that these tests are bundled. Why are these bundled, and is there any way for us to get paid for all three tests?

Connecticut Subscriber

Answer: Physicians historically performed the two older tests you mentioned together, total thyroxine (84436, Thyroxine; total) and triiodothyronine (T3) uptake (84479, Thyroid hormone [T3 or T4] uptake or thyroid hormone binding ration [THBR]). These two tests comprised the thyroid panel (80091) that was deleted in CPT 2000. The physician often used the results to calculate the free thyroxine index (FTI). Because the FTI is an indirect proportional estimate of free thyroxine (FT4), performing the newer test (84439, Thyroxine; free) provides similar diagnostic information as the old thyroid panel. If you do perform and report these codes together, you can expect Medicare denials based on the National Correct Coding Initiative (NCCI) edits, which prohibit reporting CPT 84439 with 84436 or 84479. Medicare and many private insurers use the NCCI edit pairs to detect codes that should not be paid together for the same patient on the same day because they represent services that are bundled or mutually exclusive. Because these two thyroid code edit pairs show a "0" in the NCCI modifier indicator column, you can't override these edit pairs by using modifier -59 (Distinct procedural service) as it can some edit pairs. Physician education on ordering different tests to obtain the desired results is your best solution to minimize denials for thyroid testing services.