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Test Code T4FHAMA T4, Free HAMA

Important Note

Human Anti-Mouse Antibodies (HAMA) may be present in samples from patients who have received immunotherapy utilizing monoclonal antibodies. Additionally, other heterophile antibodies such as human anti-goat antibodies may be present in patient samples. Manufacturers formulate assays to minimize the effects of these antibodies; however careful evaluation of patient results must be done when patients are known to have such antibodies.

Additional Codes

ALAB: T4FHAMA

PowerChart: T4 (Thyroxine) Free w HAMA Treatment

MA Cerner: T4, Free HAMA

Specimen Requirement

0.5 mL serum or plasma is required.

Additional Specimen Collection Information

Collect blood in a lithium heparin, green-top or red-top tube. PST and SST (gel tubes) are acceptable. Serum or plasma should be separated from contact with the cells within 2 hours of collection. Specimens not centrifuged within 4 hours of collection may be rejected. Refrigerate the specimen if unable to assay within 8 hours of collection.

Test Method

MercyOne: Two-Site Immunoassay; Beckman

MA: Immunoenzymatic ("Sandwich") Chemiluminescent Method; Roche Cobas 6000

Performance

Testing is performed Monday through Sunday.

Routine: Typically completed within 4 hours after the specimen arrives at the testing site.

STAT: Typically completed within 1.5 hours after the specimen arrives at the testing site.

Reference Values

0.61-1.12 ng/dL

  • If the assay result of the HBT treated sample is the same as the original result, the original result is reported along with the comment “HAMA not detected.”.
  • If the assay result of the HBT treated sample is not the same as the original result, the original result is not reported. The comments “Unable to report" and "HAMA detected" are reported.

CPT Code Information

84439: Chemistry: Thyroid Tests Thyroxine; Total free

NCD Frequency Limitations: 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 hyper or hypothyroidism are noted.

Useful For

The test generally is used as a second-line test after thyroid-stimulating hormone (TSH) to help evaluate TSH changes.

The Free Thyroxine value, combined with the TSH value, gives a more accurate picture of the thyroid status in patients with abnormal thyroid-binding globulin levels such as those who are pregnant or those who are receiving treatment with estrogens, androgens, phenytoin, or salicylates.

LOINC Code Information

3024-7 Thyroxine (T4) Free [Mass/Volume] In Serum Or Plasma

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