Thyroid Stimulating Immunoglobulin (TSI)
Order Name
THY ST IG
Test Number: 3603200
Revision Date 12/12/2022
Test Number: 3603200
Revision Date 12/12/2022
| Test Name | Methodology | LOINC Code |
|---|---|---|
|
Thyroid Stimulating Immunoglobulin (TSI)
|
See Test Notes | 30166-3 |
| SPECIMEN REQUIREMENTS | ||||
|---|---|---|---|---|
| Specimen | Specimen Volume (min) | Specimen Type | Specimen Container | Transport Environment |
| Preferred | 3 mL (0.3) | Serum | Clot Activator SST | Refrigerated |
| Alternate 1 | 3 mL (0.3) | Plasma | EDTA (Lavender Top) | Refrigerated |
| Alternate 2 | 3 mL (0.3) | Plasma | Lithium Heparin (Dark Green Top / No-Gel) | Refrigerated |
| Instructions | Notes: 0.3 mL (Note: This volume Does NOT allow for repeat testing.) Specimen Type: Red-top tube, gel-barrier tube, lavender-top (EDTA) tube, or green-top (heparin) tube Specimen Storage: Room Temperature Stability: Room temperature up to 24 hours Refrigerated up to 7 days Frozen up to 12 months Specimen Collection: Serum must be separated from blood cells by centrifugation, ideally within 2 hours of collection. If red-top tube is used, transfer separated serum to a plastic transport tube. Specimen Stability: Ambient: 14 days, Refrigerated : 14 days, Frozen: 14 days |
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| GENERAL INFORMATION | |
|---|---|
| Expected TAT | 2 - 4 days |
| Clinical Use | Grave's disease, also known as Exophthalmic Goiter, is the most common form of hyperthyroidism, resulting from the production of thyroid-stimulating immunoglobulin (TSI) by stimulated B lymphocytes. Positive results (123 percent or greater) are consistent with Graves disease but do not always correlate with the presence and severity of hyperthyroidism. Antibodies to the Thyroid Stimulating Hormone Receptor (TSHR) may be stimulating, blocking, or neutral. Stimulating antibodies mimic the action of TSH and cause hyperthyroidism (Graves disease). This test determines the net effect of all TSHR antibody types present in the serum specimen. |
| Notes | Methodology The IMMULITE 2000 TSI assay designed for the specific Semi- Quantitative detection of stimulating autoantibodies using a bridging format and human TSH receptor fragment chimeric recombinant proteins. The capture and detection proteins are designed to be specific for antibodies that stimulate the native receptor. This method provides a determination of thyroid stimulating autoantibodies that are specific to TSH receptors in human serum or plasma. The assay is traceable to WHO NIBSC 08/204.1 ?Labcorp Test Code: 140749 |
| CPT Code(s) | 84445 |
| Internal Comments | lionc 30166-3 added 3/2/15 -------------------- old interp Graves disease is a classic form of hyperthyroid disease, affecting approximately 0.4 percent of the population in the United States. It is caused by IgG immunoglobulins, collectively known as thyroid stimulating immunoglobulins (TSI). Patients who are candidates for antithyroid drug therapy may not respond to this treatment when TSI levels are markedly elevated. The determination of TSI can also assist in predicting hyperthyroidism in neonates due to placental transmission of the immunoglobulins from mother with a hyperthyroidism. 10/13/17 updated method - JK 02/18/20: Updated instructions - SN |
| Service Provided By |  |
| Lab Section | Reference Lab |