How To Use CPT Code 84479

CPT 84479 describes the measurement of thyroid hormone uptake or thyroid hormone binding ratio (THBR) in patient blood. This article will cover the description, procedure, qualifying circumstances, appropriate usage, documentation requirements, billing guidelines, historical information, similar codes and billing examples.

1. What is CPT Code 84479?

CPT 84479 can be used to measure the uptake of thyroid hormone or determine the thyroid hormone binding ratio in patient blood. This code is used when a lab analyst performs the necessary steps to mix patient blood with specific substances, such as labeled T3, to measure the thyroid hormone uptake. The test results are expressed as a percentage of the substance added, providing an indirect measure of the amount of thyroid hormone not bound to proteins like thyroxine binding globulin (TBG).

2. Official Description

The official description of CPT code 84479 is: ‘Thyroid hormone (T3 or T4) uptake or thyroid hormone binding ratio (THBR).’ This code falls under the range of Chemistry Procedures (82009-84999).

3. Procedure

1. The lab analyst collects a blood sample from the patient.
2. The analyst mixes the patient’s blood with specific substances, such as labeled T3, to measure the thyroid hormone uptake.
3. The lab uses methods like immunoassay to react levels of thyroxine binding globulin (TBG) antigens in the blood with reagent antibodies.
4. The lab expresses the uptake as a percentage of the substance added, providing an indirect measure of the amount of thyroid hormone not bound to proteins like TBG.
5. To determine the thyroid hormone binding ratio, the lab divides the patient’s measured uptake by a mean uptake value.

4. Qualifying circumstances

CPT 84479 is used when there is a need to measure the uptake of thyroid hormone or determine the thyroid hormone binding ratio in patient blood. This test is particularly useful in compensating for abnormal levels of TBG when diagnosing hyperthyroidism or hypothyroidism. Conditions such as pregnancy, acute hepatitis, increased estrogen, malnutrition, some liver and kidney diseases, and drug interference may produce variations in levels of T3 uptake.

5. When to use CPT code 84479

CPT code 84479 should be used when there is a need to measure the uptake of thyroid hormone or determine the thyroid hormone binding ratio in patient blood. It is important to consider the clinical circumstances and the specific diagnostic requirements before using this code.

6. Documentation requirements

To support a claim for CPT 84479, the documentation should include:

• Reason for performing the test and the clinical indication
• Details of the specific substances used and the method employed
• Date and time of the test
• Results of the thyroid hormone uptake or binding ratio
• Any relevant clinical findings or observations
• Signature of the lab analyst performing the test

7. Billing guidelines

When billing for CPT 84479, ensure that the test is performed by a qualified lab analyst and that the necessary steps are followed to measure the thyroid hormone uptake or binding ratio. It is important to review payer guidelines and policies to ensure accurate and appropriate billing. Consider any additional codes that may need to be reported in conjunction with CPT 84479, such as codes for total T4, TBG, or total T3.

8. Historical information

CPT 84479 was added to the Current Procedural Terminology system on January 1, 1990. There have been no updates to the code since its addition.

9. Examples

1. A lab analyst measures the thyroid hormone uptake in patient blood to assess thyroid function.
2. Thyroid hormone binding ratio is determined in a patient with abnormal levels of thyroxine binding globulin (TBG).
3. A test is performed to measure the uptake of thyroid hormone in a pregnant patient with suspected thyroid dysfunction.
4. The thyroid hormone binding ratio is calculated for a patient with acute hepatitis to evaluate thyroid function.
5. A lab analyst measures the thyroid hormone uptake in a patient with malnutrition to assess thyroid function.
6. Thyroid hormone binding ratio is determined in a patient with increased estrogen levels to evaluate thyroid function.
7. A test is performed to measure the uptake of thyroid hormone in a patient with liver disease to assess thyroid function.
8. The thyroid hormone binding ratio is calculated for a patient with kidney disease to evaluate thyroid function.
9. A lab analyst measures the thyroid hormone uptake in a patient taking medications that may interfere with thyroid function.
10. Thyroid hormone binding ratio is determined in a patient with suspected drug-induced thyroid dysfunction.