Pathology/Lab Coding Alert

Question: A physician ordered a thyrotropin releasing hormone stimulation panel, anti-thyroperoxidase antibody, and total thyroxine for a hypothyroid patient. How should we code this, and will Medicare cover these tests together based on the diagnosis?

New Mexico Subscriber

Answer: Whether Medicare will cover the tests you mentioned for a hypothyroid patient will depend partly on the exact diagnosis and what prior testing the patient had (and when).

For hypothyroid patients (diagnosis codes 243, Congenital hypothyroidism or 244.x, Acquired hypothyroidism), the National Coverage Determination (NCD) states that tests may be reasonable and necessary to:

• Distinguish between primary and secondary hypothyroidism

• Confirm or rule out primary hypothyroidism

• Monitor thyroid hormone levels

• Monitor drug therapy in patients with primary hypothyroidism.

Regarding testing frequency, the NCD states, "Testing may be covered up to two times a year in clinically stable patients; more frequent testing may be reasonable and necessary for patients  hose thyroid therapy has been altered or in whom symptoms or signs of hyperthyroidism or hypothyroidism are noted."

Look to these codes: Report the total thyroxine as 84436 (Thyroxine; total). The correct code for anti-thyroperoxidase antibody (TPO-Ab) is 86376 (Microsomal antibodies [e.g., thyroid or liver-kidney], each).

The physician will often order TPO-Ab to determine if the cause of hypothyroidism is an autoimmune disorder such as Hashimoto's thyroiditis (245.2, Chronic lymphocytic thyroiditis) that classifies as a primary hypothyroidism.

When preliminary lab tests show an elevated level of thyroid stimulating hormone (TSH) and a low level of total thyroxine (TT4) indicating hypothyroidism, the physician may order the antibody test to help distinguish primary and secondary hypothyroidism.

The physician may suspect a different form of hypothyroidism if the patient shows a low TT4 with a normal TSH on initial testing. To further define the diagnosis and determine if the hypothyroidism is due to pituitary dysfunction (a secondary hypothyroidism), the physician may order a thyrotropin releasing hormone stimulation panel.

Report the panel as 80438 (Thyrotropin releasing hormone [TRH] stimulation panel; one hour). This is an evocative/suppression test that involves performing three consecutive TSH tests within an hour following thyrotropin releasing hormone stimulation.

Caution: Although the lab performs three consecutive TSH tests, you should not report this service as 84443 x 3 (Thyroid stimulating hormone [TSH]). Code 80438 is a more specific code for the service.

Resource: You can view Medicare's thyroid testing NCD at www.cms.hhs.gov/CoverageGenInfo/downloads/manual201001.pdf#11.

Reader Questions and You Be the Coder were prepared with the assistance of R.M. Stainton Jr., MD, president of Doctors' Anatomic Pathology Services in Jonesboro, Ark.