Test ID: TBPE
Thyroxine-Binding Protein Electrophoresis, Serum
Secondary ID 
A test code used for billing and in test definitions created prior to November 2011
NY State Approved Indicates the status of NY State approval and if the test is orderable for NY State clients.
Useful For Suggests clinical disorders or settings where the test may be helpful
Explaining unusual thyroxine (T4), free T4, and thyroxine-binding globulin (TBG) test results that do not correlate with the clinical condition of a patient.
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.
As an adjunct to the diagnosis of patients with high T4 concentration due to peripheral hormone resistance by ruling out thyroxine-binding abnormalities.
Method Name A short description of the method used to perform the test
Electrophoretic Determination of the Major Binding Proteins of T4
Reporting Name A shorter/abbreviated version of the Published Name for a test; an abbreviated test name
Aliases Lists additional common names for a test, as an aid in searching
T4 Binders
T4 Binding Protein Electrophoresis
TBPE (Thyroxine-Binding Protein Electrophoresis)
Thyroid Binding Albumin
Thyroid Binding Prealbumin
Thyroid-Hormone Binding Electro
Thyroxine Antibodies
Thyroxine Binders
Thyroxine-Binding Protein Electrophoresis, Serum
Specimen Type Describes the specimen type needed for testing
Specimen Required Defines the optimal specimen. This field describes the type of specimen required to perform the test and the preferred volume to complete testing. The volume allows automated processing, fastest throughput and, when indicated, repeat or reflex testing.
Collection Container/Tube:
Preferred: Red top
Acceptable: Serum gel
Submission Container/Tube: Plastic vial
Specimen Volume: 0.3 mL
Additional Information: This assay measures thyroxine binding. For proteins of T4 assays of thyroxine-binding globulin, see TGBI/9263 Thyroxine-Binding Globulin (TBG), Serum and for immunologic assay of prealbumin, see PALB/9005 Prealbumin (PAB), Serum.
Specimen Minimum Volume Defines the amount of specimen required to perform an assay once, including instrument and container dead space. Submitting the minimum specimen volume makes it impossible to repeat the test or perform confirmatory or perform reflex testing. In some situations, a minimum specimen volume may result in a QNS (quantity not sufficient) result, requiring a second specimen to be collected.
Reject Due To Identifies specimen types and conditions that may cause the specimen to be rejected
| Hemolysis | Mild OK; Gross reject |
| Lipemia | Mild OK; Gross OK |
| Icterus | Mild OK; Gross OK |
| Other | NA |
Specimen Stability Information Provides a description of the temperatures required to transport a specimen to the laboratory. Alternate acceptable temperature(s) are also included.
| Specimen Type | Temperature | Time |
|---|---|---|
| Serum | Frozen (preferred) | 14 days |
| Refrigerated | 7 days | |
| Ambient | 48 hours |
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Normally, almost all (99.5%) thyroxine is bound to thyroxine-binding globulin, prealbumin, and albumin. Deficiencies and aberrant forms of these binding proteins can occur, causing difficulties interpreting thyroid function test results. Such abnormalities may be identified by thyroxine-binding protein electrophoresis.
Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
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
Other protein binders: normally not present
Thyroxine-binding globulin values may be elevated in females taking estrogens and by pregnancy.
THYROXINE, TOTAL
> or =12 months: 5.0-12.5 mcg/dL
Reference values have not been established for patients that are <12 months of age.
Interpretation Provides information to assist in interpretation of the test results
Rare protein-binding abnormalities may be suspected in euthyroid patients having an elevated total thyroxine (T4) but normal thyroxine-binding globulin (TBG).
The following example is from a healthy 40-year-old male with familial dysalbuminemic hyperthyroxinemia, a benign familial condition that can be confused with hyperthyroidism:
-Increased T4 of 14.4 mcg/dL (normal=5.0-12.5 mcg/dL)
-Normal TBG of 20.1 mcg/dL (normal=12-26 mcg/mL)
The thyroxine-binding protein electrophoresis assay identified that of the saturating dose of (125)I-T4:
-52% was bound to albumin (normal 12%-34%)
-36% was bound to thyroxine-binding prealbumin (normal 49%-70%)
-13% was bound to TBG (normal 10%-25%)
Clinical Reference Provides recommendations for further in-depth reading of a clinical nature
1. Hay ID, Klee GG: Thyroid dysfunction. Endocrinol Metab Clin North Am 1988;17:473-509
2. Bartalena L, Robbins J: Thyroid hormone transport proteins. Clin Lab Med 1993;13(3):583-598
Method Description Describes how the test is performed and provides a method-specific reference
Radioactive (125)I-T4 is incubated with serum, the mixture is electrophoresed on polyacrylamide gel, and the profile of binding proteins is quantitated by counting the radioactivity in slices of the gel. The binding proteins are separated by both charge and size with prealbumin on the anode side followed by albumin and thyroxine-binding globulin (TBG). Gamma-globulin remains at the origin, and free thyroxine (T4) migrates between albumin and prealbumin. The concentration of (125)I-T4 added will saturate TBG, but not the other T4-binders. The binding is expressed as thyroxine-binding capacity at 100 mcg T4/dL serum. (Roberts RC, Nikolai TF: Assay of thyroxine-binding globulin by polyacrylamide electrophoresis: normal values. Clin Chem 1969;5:367-375; Nikolai TF, Seal US: X-chromosome linked familial decrease in thyroxine-binding globulin activity. J Clin Endocrinol Metab 1966;26:835-841; Davis PJ, Gregerman RI: Separation of thyroxine-binding proteins in human serum at pH 7.4. II. Effect of pH and temperature on the binding capacities of thyroxine-binding globulin [TBG] and thyroxine-binding prealbumin [TBPA]. J Clin Endocrinol Metab 1971;3:699-708)
Day(s) and Time(s) Test Performed Outlines the days and times the test is performed. This field reflects the day and time the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time required before the test is performed. Some tests are listed as continuously performed, which means assays are performed several times during the day.
Wednesday; 8 a.m.
Analytic Time Defines the amount of time it takes the laboratory to setup and perform the test. This is defined in number of days. The shortest interval of time expressed is "same day/1 day," which means the results may be available the same day that the sample is received in the testing laboratory. One day means results are available 1 day after the sample is received in the laboratory.
Maximum Laboratory Time Defines the maximum time from specimen receipt at Mayo Medical Laboratories until the release of the test result
Specimen Retention Time Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded
Performing Laboratory Location The location of the laboratory that performs the test
Test Classification Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer's instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR), Investigation Use Only (IUO) product, or a Research Use Only (RUO) product.
CPT Code Information Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Medical Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.
82664
LOINC® Code Information Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the result codes returned for this test or profile.
| Result ID | Reporting Name | LOINC Code |
|---|---|---|
| 8838 | Thyroxine-Binding Protein Electro | 50681-6 |
| 2860 | TBG | 14016-0 |
| 2861 | Albumin | 11062-7 |
| 2862 | Pre-Albumin | 14014-5 |
| 2863 | Abnormal Binding Protein | In Process |
| 2899 | T4 (Thyroxine), Total Only, S | 3026-2 |
| 3345 | Comment | 48767-8 |
| 3101 | Comment | 48767-8 |
| 3102 | Comment | In Process |
| 3103 | Comment | 48767-8 |
| 3104 | Comment | 48767-8 |
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