The specimen will be evaluated for potential heterophile antibody interference in the Beckman Access Thyroglobulin (Tg) Immunoassay.
In the absence of anti-thyroglobulin antibodies, the presence of heterophile interference is not suspected when the Tg concentration in the alternate platform evaluation, dilutions, and heterophile blocking tube pretreatment are substantially altered.
Test Id | Reporting Name | Available Separately | Always Performed |
---|---|---|---|
TGII | TG, Interference Interpretation | No | Yes |
TGQN | Thyroglobulin, Tumor Marker, S | Yes, (Order HTG2) | Yes |
TGABI | Thyroglobulin Antibody, S | Yes, (Order HTG2) | Yes |
TGMS | Thyroglobulin, Mass Spec., S | Yes | Yes |
Heterophile antibody evaluation consists of comparison of thyroglobulin (Tg) concentrations obtained by immunoassay with the following:
-Tg concentrations following pretreatment with commercial heterophile blocking reagents
-Tg concentrations obtained by mass spectrometry
-Tg concentrations obtained by serial dilutions of the sample
In all samples the presence of anti-thyroglobulin antibodies are evaluated.
TGQN/TGABI: Immunoenzymatic Assay
TGMS: Tryptic Protein Fragmentation, purified with Immunocapture, Analysis by Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)
(This service is performed pursuant to an agreement with SISCAPA Assay Technologies Inc. covering US Patent 7,632,686)
TGII: Medical Interpretation
TG Heterophile
HTG
TG (Thyroglobulin)
Thyroglobulin Assay for Thyroid Cancer
Heterophile antibody evaluation consists of comparison of thyroglobulin (Tg) concentrations obtained by immunoassay with the following:
-Tg concentrations following pretreatment with commercial heterophile blocking reagents
-Tg concentrations obtained by mass spectrometry
-Tg concentrations obtained by serial dilutions of the sample
In all samples the presence of anti-thyroglobulin antibodies are evaluated.
Serum Red
If interference or heterophile testing is not required, order HTG2 / Thyroglobulin, Tumor Marker, Serum.
For fine-needle aspirate specimens, order TFNAB / Thyroglobulin, Tumor Marker, Fine-Needle Aspiration Biopsy Needle Wash.
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: Red top (serum gel/SST are not acceptable)
Submission Container/Tube: Plastic vial
Specimen Volume: 2.5 mL
2 mL
Gross hemolysis | Reject |
Thawing** | Cold OK; Warm <72 hours OK |
Gross lipemia | OK |
Gross icterus | Reject |
Specimen Type | Temperature | Time | Special Container |
---|---|---|---|
Serum Red | Refrigerated (preferred) | 7 days | |
Frozen | 30 days | ||
Ambient | 72 hours |
Heterophile antibody evaluation consists of comparison of thyroglobulin (Tg) concentrations obtained by immunoassay with the following:
-Tg concentrations following pretreatment with commercial heterophile blocking reagents
-Tg concentrations obtained by mass spectrometry
-Tg concentrations obtained by serial dilutions of the sample
In all samples the presence of anti-thyroglobulin antibodies are evaluated.
Most often Tg is measured by immunometric assays as they are widely available in automated high-throughput instruments, have shorter turnaround times, and have functional sensitivities of 0.1 mcg/L or less. However, these immunoassays may be affected by the presence of both anti-thyroglobulin antibody (TgAb) and heterophile antibody interferences. The presence of TgAb might cause falsely low/undetectable Tg that can mask disease; whereas heterophile antibodies might cause falsely high Tg that can be mistaken for residual or recurrent disease.
Some patients, due to exposure to animal antigens, have developed heterophile antibodies, such as human anti-mouse antibodies (HAMA), that can interfere with immunoassay testing by binding to the animal antibodies used in immunoassays. In some sandwich immunoassays, including those for Tg, the presence of heterophile antibodies in the patient’s sample might lead to a false-positive result.
Although rare, false-negative assay results due to heterophile interference have also been reported in the literature. Manufacturers often add blocking agents to their reagents, but, occasionally, patient samples containing heterophile antibodies are incompletely blocked and exhibit heterophile antibody interference. Subsequent reporting of erroneous results can have adverse effects on patient management, especially with tumor marker assays.
Dilution of the specimen prior to assay performance often yields unexpected nonlinear results in the presence of interfering substances such as heterophile antibodies and/or TgAb. Heterophile blocking tube (HBT) treatment is also utilized for troubleshooting samples that exhibit potential heterophile interference. Finally, assessment of an analyte such as Tg with an alternative assay will often lead to apparent discrepant results in the presence of heterophile antibodies and/or TgAb interference.
Measurement of Tg by liquid chromatography-tandem mass spectrometry (Tg-MS) has been introduced as a method for accurate Tg quantitation in the presence of TgAb and heterophile antibodies. Tg-MS assays are based on peptide quantitation after tryptic digestion and immunocapture of Tg-specific peptides. The advantage of trypsin digestion is that all proteins are cleaved, including both TgAb and heterophile antibodies, thus eliminating them as interferences.
THYROGLOBULIN TUMOR MARKER
Intact thyroid: < or =33 ng/mL
THYROGLOBULIN, MASS SPECTROMETRY
Athyrotic: <0.2 ng/mL
Healthy individuals with intact, functioning thyroid: < or =33 ng/mL
THYROGLOBULIN ANTIBODY
<1.8 IU/mL
Reference values apply to all ages.
Specimens are evaluated for the presence of potential interfering anti-thyroglobulin (TgAb) and heterophile antibody interference in the Beckman Access thyroglobulin (Tg) immunoassay. While the presence of TgAb can result in falsely low Tg concentrations in the Beckman immunoassay, the presence of heterophile antibodies can result in falsely elevated Tg concentrations in the Beckman immunoassay. Following investigation of the presence of TgAb, heterophile antibody evaluation consists of pretreatment with commercial heterophile antibody blocking reagents, serial dilutions of the sample, and testing on an alternate platform generally unaffected by the presence of heterophile antibodies or TgAb (ie, Tg liquid chromatography-tandem mass spectrometry [Tg-MS]). The presence of heterophile antibody interference in the Beckman Access Tg immunoassay is not suspected when the results from the pretreatment, serial dilutions, and the alternative platform (Tg-MS) agree with the original result.
The presence of heterophile antibody interference in the Beckman Access Tg immunoassay is suspected when 1 or more of the following are observed: a significant decrease in Tg concentration (>20%) upon treatment of the sample with heterophile antibody blocking reagents, lack of linearity upon serial dilutions, or a significant difference in Tg concentration on the alternate platform (Tg-MS). When a heterophile antibody interference affecting the Beckman Access immunoassay is suspected, the Tg result from this assay is considered false positive and should not be used in clinical management.
Thyroglobulin Antibody:
There may be some samples with extremely strong heterophile interference. In such cases heterophile blocking reagents may not be able to block all the assay interference.
Specimens with thyroglobulin (Tg) concentrations greater than 250,000 ng/mL may "hook" and appear to have markedly lower levels.
Tg and anti-thyroglobulin (TgAb) values determined by different methodologies might vary significantly and cannot be directly compared with one another. Some patients might have antibody-positive results by some methods and antibody-negative results by others. Comparing values from different methods might lead to erroneous clinical interpretation.
Rare normal amino acid sequence variations within Tg can cause a false-low result in the Tg mass spectrometry assay, if they happen to be present in the Tg proteotypic peptides that are used for Tg quantification. While the exact prevalence of such changes is unknown, validation data on large sample numbers indicate that this affects less than 1% of samples. In the heterozygote state, the result would be an apparent reduction in Tg concentration by about 50%, while the homozygous state (<0.01%) is predicted to result in total loss of signal.
2. American Thyroid Association (ATA) Guidelines Taskforce on Thyroid Nodules and Differentiated Thyroid Cancer, Cooper DS, Doherty GM, et al: Revised American Thyroid Association management guidelines for patients with thyroid nodules and differentiated thyroid cancer. Thyroid. 2009 Nov;19(11):1167-1214
3. Netzel BC, Grebe SKG, Algeciras-Schimnich A: Usefulness of a thyroglobulin liquid chromatography-tandem mass spectrometry assay for evaluation of suspected heterophile interference. Clin Chem. 2014 Jul;60(7):1016-1018
4. Algeciras-Schimnich A: Thyroglobulin measurement in the management of patients with differentiated thyroid cancer. Crit Rev Clin Lab Sci. 2018 May;55(3):205-218
5. Ward G, Simpson A, Boscato L, Hickman PE: The investigation of interferences in immunoassay. Clin Biochem. 2017 Dec;50(18):1306-1311
The specimen will be evaluated for potential heterophile antibody interference in the Beckman Coulter Access Thyroglobulin Immunoassay. Heterophile antibody evaluation will consist of measurement of thyroglobulin antibody, pretreatment with commercial heterophile antibody blocking reagents, testing on an alternate platform liquid chromatography-tandem mass spectrometry (LC-MS/MS), and serial dilution of the sample.
Heterophile blocking agents consisted of HBT (Heterophile Blocking Tube) - Scantibodies Incorporated for the Beckman Assay. This blocker contains murine (HBT) derived proteins in a buffered salt solution.
Thyroglobulin, Tumor Marker:
Thyroglobulin Antibody:
Thyroglobulin, Alternative Method:
Serum is fractionated by a salting out method. Fractionated serum is then reduced, alkylated, and digested with trypsin. Tryptic fragments are further purified by immunocapture with antibodies specific to the individual fragments. Finally, these fragments are analyzed by LC-MS/MS.(Unpublished Mayo method)
Thyroglobulin, Interference Interpretation:
A laboratory director will review the results and provide an interpretation.
Monday through Friday
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 US Food and Drug Administration.
84432
86800
84432
Test Id | Test Order Name | Order LOINC Value |
---|---|---|
IETG | Interference Eval, Heterophile, TG | In Process |
Result Id | Test Result Name |
Result LOINC Value
Applies only to results expressed in units of measure originally reported by the performing laboratory. These values do not apply to results that are converted to other units of measure.
|
---|---|---|
62749 | Thyroglobulin, Mass Spec., S | 3013-0 |
35998 | Interpretation | 59462-2 |
TGABI | Thyroglobulin Antibody, S | 56536-6 |
TGQN | Thyroglobulin, Tumor Marker, S | In Process |
TGIF | TG, Interference Heterophile | In Process |
TGIN | TG, Interpretation | In Process |
Change Type | Effective Date |
---|---|
Test Status - Test Resumed | 2022-08-10 |
Test Status - Test Delay | 2022-07-29 |
New Test | 2021-10-07 |