Sign in →

Test Code Billings Clinic: 4375 Thyroid Function Cascade, Plasma or Serum

Important Note

Although the Free T3 and Free T4 assays are FDA Approved for other patient populations these assays performance characteristics have not been established for neonates.

Performing Laboratory

Billings Clinic Laboratory:  Chemistry

Useful For

This is a testing protocol to evaluate and monitor thyroid function, to screen for thyroid disease, and to diagnose thyroid disease.

Methodology

See individual test listings

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 3 mL of plasma divided into 3 plastic vials, each containing 1 mL of plasma.
  • Send specimens frozen.

 

Serum

  • Draw blood in a plain, red-top tube(s) or a serum gel tube(s).
  • Spin down and send 3 mL of serum divided into 3 plastic vials, each containing 1 mL of serum.
  • Send specimens frozen.

Reject Due To

  • Gross hemolysis
  • Specimens with apparent contamination
  • Specimens stored at room temperature greater than 8 hours
  • Samples frozen and thawed more than once

Reference Values

See individual test listings

Day(s) Test Set Up

Daily

Test Classification and CPT Coding

84443 - TSH

84439 - T4, free (if appropriate)

84480 - T3, total (if appropriate)

86376 - microsomal antibodies; thyroid or liver-kidney (if appropriate)

 

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
T4, Free (if appropriate) 3024-7
T3, Total (if appropriate) 3053-6
TPO Ab (if appropriate) 56477-3

 

Profile/Testing Information

Profile Information:
Thyroid-Stimulating Hormone (TSH)  
Reflex Tests (at an additional charge):
Thyroperoxidase (TPO) Antibodies T4 (Thyroxine), Free
T3 (Triiodothyronine), Total Only  

Reflex Information:

  • Testing begins with Billings Clinic: #4056 “Thyroid-Stimulating Hormone (TSH), Plasma or Serum.”
  • If TSH level is >4.78 µIU/mL; Billings Clinic: #8103 “T4 (Thyroxine), Free, Plasma or Serum” and Billings Clinic: #7079 “Thyroperoxidase (TPO) Antibodies, Plasma or Serum” will be performed.
  • If TSH level is <0.55 µIU/mL; Billings Clinic: #8103 “T4 (Thyroxine), Free, Plasma or Serum” will be performed.
  • If free T4 level is normal; Billings Clinic: #8986 “T3 (Triiodothyronine), Total Only, Plasma or Serum” will be performed.

This test order is a reflexive panel. By ordering this panel, the ordering physician/nonphysician provider (NPP) consents and understands that they are giving a specific order that includes the performance of further testing as indicated by reflexive criteria. Individual tests may be ordered in place of this panel.