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Test Code THSC Thyroid Stimulating Hormone (TSH) Cascade LAB2754

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.

Test Method

Two-Site Immunoenzymatic (“Sandwich”) Assay; Beckman Access II

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

Reference Values

0.3-5.6 mcIU/mL


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.

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

An aid in the diagnosis of primary hyperthyroidism

Differential diagnosis of hypothyroidism


LOINC Code Information

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

CPT Code Information

84443 Chemistry: Thyroid Stimulating

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.

Test Algorithm

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