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Thyroid-stimulating Immunoglobulin (TSI)

Alternate Name: TSI_Immulite

SAL Code:

1092

CPT:

84445

Loinc:

30567-2

Units:

IU/L

Department:

Endocrinology

Methodology:

Test Methodology:
The IMMULITE 2000 TSI assay is an automated, two-cycle, chemiluminescent immunoassay. It employs a pair of recombinant hTSHR constructs in a bridging immunoassay format. The capture receptor is immobilized on the solid phase (polystyrene bead). The signal receptor is an alkaline phosphatase labeled recombinant hTSHR in a buffer solution.

Specimen Requirements:

Primary Tube:

SST

Primary Substance:

Serum

Temperature

Period

Stable Ambient:

24 hours

Stable Fridge:

7 days

Stable Frozen:

-20 degrees 12 Months

Additional Information:

Test Clinical Use Information:
The IMMULITE 2000 TSI assay is an in vitro diagnostic immunoassay for the semi quantitative determination of thyroid stimulating autoantibodies specific to TSH receptors in human serum (including serum separator tubes) or plasma (K2-EDTA or lithium heparin). The IMMULITE TSI assay is for use with the IMMULITE® 2000 System. The measurement of thyroid stimulating autoantibodies, in conjunction with other clinical and laboratory findings, is used as an aid in the diagnosis of patients suspected of having Graves’ disease.

Test Limitations:

Test Clinical Limitations:
High-dose Hook Effect
No effect up to 800 IU/L
The cross reactivity of the IMMULITE 2000 TSI assay with FSH, LH, TSH, hCG, anti-TG, and anti-TPO was determined by adding these hormones to TSI-free human serum.

Cross Reactivity Compound:

-Follicie Stimulating Hormone (FSH)
Added IU/L: 750
Apparent Dose (IU/L): ND

-Luteinizing Hormone(LH)
Added IU/L: 500
Apparent Dose (IU/L): ND

-Thyroid-Stimulating Hormone(TSH)
Added IU/L: 0.14
Apparent Dose (IU/L): ND

-Human Chorionic gonadotropin (hcG)
Added IU/L: 100.000
Apparent Dose (IU/L): 0.01

-Anti-Thyroglobulin (aTG)
Added IU/L: 2.000.000
Apparent Dose (IU/L): ND

-Anti-Thyroid-Stimulating Peroxidase (aTPO)
Added IU/L: 2.000.000
Apparent Dose (IU/L): ND

ND: Not Detected


Bilirubin
Presence of conjugated and unconjugated bilirubin in concentrations up to 40 mg/dL has no effect on results, within the precision of the assay.
Hemolysis
Presence of hemoglobin at a concentration of 200 mg/dL may affect recovery.
Lipemia
Presence of triglycerides in concentrations up to 1000 mg/dL has no effect on results, within the precision of the assay.
Rheumatoid Factor
Samples containing up to 200 IU/mL of Rheumatoid Factors cause no interference.
Other
Heterophilic antibodies in human serum can react with the immunoglobulins included in the assay components causing interference with in vitro immunoassays. Samples from patients routinely exposed to animals or animal serum products can demonstrate this type of interference potentially causing an anomalous result. These reagents have been formulated to minimize the risk of interference; however, potential interactions between rare sera and test components can occur. For diagnostic purposes, the results obtained from this assay should always be used in combination with the clinical examination, patient medical history, and other findings.

Test Information:

Components: