Test Id : THYRO
Thyrotropin Receptor Antibody, Serum
Useful For
Suggests clinical disorders or settings where the test may be helpful
Recommended first-line test for detection of thyrotropin receptor antibodies
Differential diagnosis of etiology of thyrotoxicosis in patients with ambiguous clinical findings and/or contraindicated (eg, pregnant or breast-feeding) or nondiagnostic thyroid radioisotope scans
Diagnosing clinically suspected Graves disease (GD) (eg, extrathyroidal manifestation of GD include endocrine exophthalmos, pretibial myxedema, thyroid acropachy) in patients with normal thyroid function tests
Determining the risk of neonatal thyrotoxicosis in a fetus of a pregnant female with active or past active GD
Differential diagnosis of gestational thyrotoxicosis versus first trimester manifestation or recurrence of GD
Assessing the risk of GD relapse after antithyroid drug treatment
Method Name
A short description of the method used to perform the test
Electrochemiluminescence Immunoassay
NY State Available
Indicates the status of NY State approval and if the test is orderable for NY State clients.
Reporting Name
Lists a shorter or abbreviated version of the Published Name for a test
Aliases
Lists additional common names for a test, as an aid in searching
Antibodies to TSH receptor
Inhibitory Immunoglobulin
Long-Acting Thyroid Stimulator (LATS)
TBII (TSH-Binding Inhibiting Immunoglobulin)
Thyroid-Stimulating Hormone Receptor (TSH Receptor) Antibody
TRAb (Thyrotropin Receptor Antibody)
TSH (Thyroid-Stimulating Hormone) Receptor Binding
TSH Binding Inhibition Index
TSH Receptor (Thyroid-Stimulating Hormone Receptor) Antibody
TSH-Binding Inhibiting Immunoglobulin (TBII)
Graves Disease
Graves' Disease
Specimen Type
Describes the specimen type validated for testing
Serum
Specimen Required
Defines the optimal specimen required to perform the test and the preferred volume to complete testing
Patient Preparation:
1. For 12 hours before specimen collection. patient should not take multivitamins or dietary supplements (eg, hair, skin, and nail supplements) containing biotin (vitamin B7).
2. Patient should not be receiving heparin treatment.
Supplies: Sarstedt Aliquot Tube, 5 mL (T914)
Collection Container/Tube:
Preferred: Serum gel
Acceptable: Red top
Submission Container/Tube: Plastic vial
Specimen Volume: 1 mL
Collection Instructions: Centrifuge and aliquot serum into a plastic vial.
Forms
If not ordering electronically, complete, print, and send a General Request (T239) with the specimen.
Specimen Minimum Volume
Defines the amount of sample necessary to provide a clinically relevant result as determined by the testing laboratory. The minimum volume is sufficient for one attempt at testing.
0.75 mL
Reject Due To
Identifies specimen types and conditions that may cause the specimen to be rejected
| Gross hemolysis | Reject |
| Gross lipemia | OK |
| Gross icterus | Reject |
Specimen Stability Information
Provides a description of the temperatures required to transport a specimen to the performing laboratory, alternate acceptable temperatures are also included
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Serum | Refrigerated (preferred) | 7 days | |
| Frozen | 90 days |
Useful For
Suggests clinical disorders or settings where the test may be helpful
Recommended first-line test for detection of thyrotropin receptor antibodies
Differential diagnosis of etiology of thyrotoxicosis in patients with ambiguous clinical findings and/or contraindicated (eg, pregnant or breast-feeding) or nondiagnostic thyroid radioisotope scans
Diagnosing clinically suspected Graves disease (GD) (eg, extrathyroidal manifestation of GD include endocrine exophthalmos, pretibial myxedema, thyroid acropachy) in patients with normal thyroid function tests
Determining the risk of neonatal thyrotoxicosis in a fetus of a pregnant female with active or past active GD
Differential diagnosis of gestational thyrotoxicosis versus first trimester manifestation or recurrence of GD
Assessing the risk of GD relapse after antithyroid drug treatment
Clinical Information
Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Autoimmune thyroid disease is characterized by the presence of autoantibodies against various thyroid components, namely the thyrotropin receptor, thyroid peroxidase, and thyroglobulin, as well as by an inflammatory cellular infiltrate of variable severity within the gland.
Among the autoantibodies found in autoimmune thyroid disease, thyrotropin receptor autoantibodies (TRAb) are most closely associated with disease pathogenesis. All forms of autoimmune thyrotoxicosis (Graves disease [GD], Hashitoxicosis, neonatal thyrotoxicosis) are caused by the production of stimulating TRAb. These autoantibodies, also known as long-acting-thyroid-stimulators or thyroid-stimulating immunoglobulins (TSI), bind to the receptor and transactivate it, leading to stimulation of the thyroid gland independent of the normal feedback-regulated thyrotropin stimulation.
Some patients with GD also have TRAb that do not transactivate the thyrotropin receptor. The balance between stimulating and blocking antibodies, as well as their individual titers, is felt to be a determinant of GD severity. Some patients with autoimmune hypothyroidism also have evidence of either blocking TRAb or, rarely, TSI.
Thyrotropin receptor autoantibodies may be detected before autoimmune thyrotoxicosis becomes biochemically or clinically manifest. Since none of the treatments for GD are aimed at the underlying disease process but rather ablate thyroid tissue or block thyroid hormone synthesis, TSI may persist after apparent clinical cure. This is of particular relevance for pregnant women with a history of GD treated with thyroid-ablative therapy. Some of these women may continue to produce TSI. Since TSI are IgG antibodies, they can cross the placental barrier causing neonatal thyrotoxicosis.
While the gold standard for thyroid-stimulating immunoglobulins is the bioassay (see TSI / Thyroid-Stimulating Immunoglobulin, Serum), the TRAb test has a shorter turnaround time, less analytical variability, and is less expensive.
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.
< or =1.75 IU/L
Interpretation
Provides information to assist in interpretation of the test results
The sensitivity and specificity of an elevated thyrotropin receptor antibody (TRAb) test for Graves disease (GD) diagnosis depends on whether patients have disease treated with antithyroid drugs or clinically active, untreated disease. Based on a study that included specimens from 436 apparently healthy individuals, 210 patients with thyroid diseases without diagnosis of GD, and 102 patients with untreated GD, a decision limit of 1.75 IU/L showed a sensitivity of 97% and a specificity of 99% for detection of GD.(1) In healthy individuals and in patients with thyroid disease without diagnosis of GD, the upper limit of antithyrotropin receptor values are 1.22 IU/L and 1.58 IU/L, respectively (97.5th percentiles). A Mayo study of 115 patients, including 42 patients with GD, showed a sensitivity of 95% and a specificity of 97% for detection of GD at a decision limit of 1.75 IU/L.
Assessment of TRAb status is particularly relevant in women who have undergone thyroid ablative therapy or are on active antithyroid treatment and, therefore, no longer display biochemical or clinical evidence of thyrotoxicosis. Significant neonatal thyrotoxicosis is likely if a pregnant woman with a history of GD has TRAb concentrations of more than 3.25 IU/L during the last trimester, regardless of her clinical remission status. Lesser elevations are only occasionally associated with neonatal thyrotoxicosis.
Gestational thyrotoxicosis, which is believed to be due to a combination of human chorionic gonadotropin cross-reactivity on the thyrotropin receptor and transient changes in thyroid hormone protein binding, is only very rarely associated with an elevated TRAb test. Finding an elevated test result in this setting usually suggests underlying GD.
An elevated TRAb test at the conclusion of a course of antithyroid drug treatment is highly predictive of relapse of GD. However, the converse, a normal TRAb test, is not predictive of prolonged remission.
Cautions
Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
In rare cases, some individuals can develop antibodies to mouse or other animal antibodies (often referred to as human anti-mouse antibodies [HAMA] or heterophile antibodies), which may cause interference in some immunoassays. The presence of antibodies to streptavidin or ruthenium can also rarely occur and may also interfere in this assay. Caution should be used in interpretation of results, and the laboratory should be alerted if the result does not correlate with the clinical presentation.
Supportive Data
A Mayo method comparison study between this assay and the Kronus TSH Receptor Antibody binding inhibition assay showed an overall agreement between the assays of 96.5% and a calculated Kappa statistic of 0.93.
Clinical Reference
Recommendations for in-depth reading of a clinical nature
1. Schott M, Hermsen D, Broecker-Preuss M, et al. Clinical value of the first automated TSH receptor autoantibody assay for the diagnosis of Graves disease: an international multicentre trial. Clin Endocrinol (Oxf). 2009;71(4):566-573
2. Hermsen D, Broecker-Preuss M, Casati M, et al. Technical evaluation of the first fully automated assay for the detection of TSH receptor autoantibodies. Clin Chim Acta. 2009;401(1-2):84-89
3. Diana T, Olivo PD, Kahaly GJ. Thyrotropin receptor blocking antibodies. Horm Metab Res. 2018;50(12):853-862
4. Kotwal A, Stan M. Thyrotropin receptor antibodies-an overview. Ophthalmic Plast Reconstr Surg. 2018; 34(4S Supple 1)S20-S27
Method Description
Describes how the test is performed and provides a method-specific reference
The Roche TSHR (thyrotropin receptor antibody [TRAb]) assay is a competitive assay using electrochemiluminescence detection. Patient sample is treated with a reagent buffer consisting of a pre-formed immunocomplex of solubilized porcine thyrotropin (TSH) receptor and biotinylated anti-porcine TSH receptor mouse monoclonal antibody. TRAb in the patient's sample are allowed to interact with the TSH receptor complex. After addition of streptavidin-coated microparticles and a human thyroid-stimulating monoclonal autoantibody (M22) labeled with a ruthenium complex, bound TRAb are detected by their ability to inhibit the binding of labeled M22. The entire complex becomes bound to the solid phase via interaction of biotin and streptavidin. This reaction mixture is aspirated into a measuring cell where the bound microparticles are captured onto the electrode surface and unbound substances are removed. Voltage is applied to the electrode inducing a chemiluminescent emission, which is then measured against a calibration curve to determine the amount of thyrotropin receptor antibody in the patient specimen.(Package insert: Elecsys Anti-TSHR. Roche Diagnostics; V 3.0, 09/2023)
PDF Report
Indicates whether the report includes an additional document with charts, images or other enriched information
Day(s) Performed
Outlines the days the test is performed. This field reflects the day that the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time before the test is performed. Some tests are listed as continuously performed, which means that assays are performed multiple times during the day.
Monday through Saturday
Report Available
The interval of time (receipt of sample at Mayo Clinic Laboratories to results available) taking into account standard setup days and weekends. The first day is the time that it typically takes for a result to be available. The last day is the time it might take, accounting for any necessary repeated testing.
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
Indicates the location of the laboratory that performs the test
Fees :
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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 instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR) product.
This test has been cleared, approved, or is exempt by the US Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.
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 Clinic Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.
CPT codes are provided by the performing laboratory.
CPT codes are provided by the performing laboratory.
83520
LOINC® Information
Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the order and results codes of this test. LOINC values are provided by the performing laboratory.
| Test Id | Test Order Name | Order LOINC Value |
|---|---|---|
| THYRO | Thyrotropin Receptor Ab, S | 5385-0 |
| 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.
|
|---|---|---|
| THYRO | Thyrotropin Receptor Ab, S | 5385-0 |