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Test Code TSHCR 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


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


Specimen Requirement

0.5 mL serum or plasma is required.

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.

Reference Values

0.3-5.6 mcIU/mL

LOINC Code Information

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

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

Test Algorithm

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