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Thyroid Stimulating Immunoglobulin (TSI)

Order Name THY ST IG
Test Number: 3603200
Revision Date 02/18/2020
Test Name Methodology LOINC Code
Thyroid Stimulating Immunoglobulin (TSI)
Semi-Quant Bioassay/Quant Chemiluminescent Immunoassay 30166-3 
Specimen Specimen Volume (min) Specimen Type Specimen Container Transport Environment
Preferred 1 mL (0.5) Serum Clot Activator SST Refrigerated
Alternate 1 1 mL (0.5) Plasma EDTA (Lavender Top) Refrigerated
Alternate 2 1 mL (0.5) Plasma Lithium Heparin (Dark Green Top / No-Gel) Refrigerated
Instructions Collect: Green (Lithium Heparin), or Lavender (K+ EDTA). 
Specimen Preparation: Allow specimen to clot completely at room temperature. Separate from cells ASAP or within 2 hours of collection. 
Specimen Stability: After separation from cells: Ambient 24 hours; Refrigerated 1 week; Frozen 1 year.
Testing Schedule Sun-Sat 
Expected TAT 1-2 Days after set-up  
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 Reference Lab: ARUP
Test Code: 3002287
Click Here to view information on the ARUP website.
CPT Code(s) 84445
Lab Section Reference Lab