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Test Code 361 Thyroid Stimulating Hormone (TSH) Cascade

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: TSHCAS

PowerChart: Thyroid Stimulating Hormone (Reflex FT4)

MA Cerner: TSH Cascade.

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. Grossly hemolyzed specimens are not acceptable. Samples with >3+ lipemia must be cleared prior to analysis.

Useful For

Monitoring patients on thyroid replacement therapy

Confirmation of thyroid-stimulating hormone (TSH) suppression in thyroid cancer patients on thyroxine therapy

Prediction of thyrotropin-releasing hormone-stimulated TSH response

An aid in the diagnosis of primary hyperthyroidism

Differential diagnosis of hypothyroidism

 

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.

CPT Code Information

84443 Chemistry: Thyroid Stimulating Hormone

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.

LOINC Code Information

11580-8 Thyrotropin [Units/volume] in Serum or Plasma by Detection limit ≤ 0.005 mIU/L

Test Method

MercyOne: Two-Site Immunoenzymatic ("Sandwich") Assay; Beckman

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

Reference Values

0.3-5.6 mcIU/mL

Test Algorithm

A Free T4 will be performed and reported at additional charge when the TSH results are outside the published reference range.