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Test Code Billings Clinic: 4056 Thyroid-Stimulating Hormone (TSH), Plasma or Serum

Important Note

Although this assay is FDA Approved for other patient populations the assay performance characteristics have not been established for neonates.

Do not use samples that contain fluorescein.  Fluorescein levels >0.24 µg/mL may decrease results in this assay.  Evidence suggests that patients undergoing retinal fluorescein angiography can retain amounts of fluorescein in the body for up to 48-72 hours post-treatment.

Performing Laboratory

Billings Clinic Laboratory: Chemistry

Useful For

  • Screening for thyroid dysfunction and detecting mild (subclinical), as well as overt, primary hypo- or hyperthyroidism in ambulatory patients
  • Monitoring patients on thyroid replacement therapy
  • Confirmation of thyroid-stimulating hormone (TSH) suppression in thyroid cancer patients on thyroxine suppression therapy
  • Prediction of thyrotropin-releasing hormone-stimulated TSH response

Methodology

Chemiluminescence

Specimen Requirements

Submit only 1 of the following specimens:

Serum or plasma should be physically separated from cells as soon as possible with a maximum limit of two hours from the time of collection.

 

Plasma

  • Draw blood in a green-top (lithium heparin) tube(s).
  • Spin down and send 1.0 mL of heparinized plasma frozen.

 

Serum

  • Draw blood in a plain, red-top tube(s) or a serum gel tube(s).
  • Spin down and send 1.0 mL of serum frozen

Storage/Stability

Specimen Type Temperature Time
Plasma Refrigerated 2 days
  Frozen (preferred) 2 weeks
  Ambient 1 day
Serum Refrigerated 2 days
  Frozen (preferred) 1 month
  Ambient 1 day
     

 

Reject Due To

  • Samples with apparent contamination
  • Samples frozen and thawed more than once
  • Gross hemolysis

Reference Values

0 - 1 day:  1.00 - 20.00 µIU/mL

1 - 3 days:  0.50 - 8.00 µIU/mL

3 days to 6 months:  0.50 - 6.00 µIU/mL

6 months - 5 years:   0.50 - 5.50 µIU/mL

5 - 13 years:  0.50 - 5.00 µIU/mL

> 13 years: 0.55 - 4.78 µIU/mL

Day(s) Test Set Up

Daily

Test Classification and CPT Coding

84443 - TSH

 

LCD or NCD test. ICD-10 code is required for this test. When appropriate, obtain a properly executed ABN and submit the ABN with test order(s). See “Medical Necessity and Advanced Beneficiary Notice (ABN) Policy and Form” under Resources for a copy of a form and additional information.

LOINC Code Information

Reporting Name LOINC Code
TSH 11579-0