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Specimen Collection Manual and Test Catalog

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TSI (THYROID STIMULATING IMMUNOGLOBULIN)

Geisinger Epic Procedure Code:  LAB3161    Geisinger Epic ID:  17556

SPECIMEN COLLECTION
Specimen type: 

Serum


Preferred collection container: 
Specimen required: 

1 mL aliquot of serum; minimum 0.2 mL.



SPECIMEN PROCESSING
Processing instructions: 

Centrifuge and transfer serum specimens to clean, plastic, screw-capped vial(s). Transport on refrigerant coolant.


Transport temperature: 

Refrigerated.


Specimen stability: 

Refrigerated: 21 days (preferred). Frozen: 60 days.


Rejection criteria: 

Room temperature specimens will be rejected. Grossly hemolyzed, iteric and lipemic specimens will be rejected.



TEST DETAILS
Reference interval: 

< 140% of baseline.


Additional information: 

Please note: A serum TSH level >25 uIU/mL can interfere with the TSI bioassay, and potentially give higher TSI results


CPT code(s):  84445
Note: The billing party has sole responsibility for CPT coding.  Any questions regarding coding should be directed to the payer being billed.
The CPT codes provided by GML are based on AMA guidelines and are for informational purposes only.

Test includes: 

Thyroid Stimulating Immunoglobulin


Methodology: 
Immunoassay
Synonyms: 

Thyroid Stimulating Immun, THSI, Quest test code 30551


Clinical significance: 

Graves' disease is a classic form of hyperthyroid disease, affecting approximately 0.4% 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 a mother with hyperthyroidism.


Review Date:  11/28/2024

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