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Test Code T4BPE Thyroxine-Binding Protein Electrophoresis, Serum

Useful For

Explaining unusual thyroxine (T4), free T4, and thyroxine-binding globulin (TBG) test results that do not correlate with the patient’s clinical presentation

 

Detecting the presence of aberrant thyroxine-binding proteins such as abnormal forms of albumin and prealbumin

 

Detecting selective deficiency of one of the thyroxine-binding proteins

 

Detecting antibodies to T4

 

An adjunct to the diagnosis of patients with high T4 concentration due to peripheral hormone resistance by ruling out thyroxine-binding abnormalities

Profile Information

Test ID Reporting Name Available Separately Always Performed
TBPE Thyroxine-Binding Protein Electro No Yes
T4 T4 (Thyroxine), Total Only, S Yes Yes

Method Name

TBPE: Electrophoresis

T4: Electrochemiluminescence Immunoassay

Reporting Name

Thyroxine-Binding Protein Electro

Specimen Type

Serum


Advisory Information


This assay measures thyroxine binding to various proteins.

 

For analysis of thyroxine-binding globulin, see TBGI / Thyroxine-Binding Globulin (TBG), Serum.

For immunologic assay of prealbumin, see PALB / Prealbumin, Serum.

 

This test should not be requested in patients who have recently received radioisotopes, therapeutically or diagnostically, because of potential assay interference. A recommended time period before collection cannot be made because it will depend on the isotope administered, the dose given, and the clearance rate in the individual patient.

 

The total T4 test should not be used in patients receiving treatment with lipid-lowering agents containing dextrothyroxine unless therapy is discontinued for 4 to 6 weeks to allow the T4 physiological state to become re-established prior to testing.



Specimen Required


Patient Preparation: For 12 hours before specimen collection, do not take multivitamins or dietary supplements containing biotin (vitamin B7), which is commonly found in hair, skin, and nail supplements and multivitamins.

Collection Container/Tube:

Preferred: Serum gel

Acceptable: Red top

Submission Container/Tube: Plastic vial

Specimen Volume: 1.6 mL


Specimen Minimum Volume

0.8 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Serum Refrigerated (preferred) 7 days
  Frozen  14 days

Reference Values

THYROXINE-BINDING PROTEIN ELECTROPHORESIS

10.3-24.9 mcg T4/dL bound to TBG

11.5-34.1 mcg T4/dL bound to albumin

48.8-70.4 mcg T4/dL bound to prealbumin

 

T4 (THYROXINE), TOTAL ONLY

Adult (≥20 years): 4.5-11.7 mcg/dL

Pediatric:

0-5 days: 5.0-18.5 mcg/dL

6 days-2 months: 5.4-17.0 mcg/dL

3-11 months: 5.7-16.0 mcg/dL

1-5 years: 6.0-14.7 mcg/dL

6-10 years: 6.0-13.8 mcg/dL

11-19 years: 5.9-13.2 mcg/dL

Day(s) and Time(s) Performed

Once per month

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Test Classification

This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the U.S. Food and Drug Administration.

CPT Code Information

TBPE: 82664

T4: 84436

LOINC Code Information

Test ID Test Order Name Order LOINC Value
T4BPE Thyroxine-Binding Protein Electro 48073-1

 

Result ID Test Result Name Result LOINC Value
2860 TBG 14016-0
2861 Albumin 11062-7
T4 T4 (Thyroxine), Total Only, S 83119-8
2862 Pre-Albumin 14014-5
2863 Abnormal Binding Protein 48767-8
3345 Comment 50681-6