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HelpTest Code TSI Thyroid-Stimulating Immunoglobulin, Serum
Test Down Notes
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Performing Laboratory
Mayo Clinic Laboratories in Rochester
Specimen Type
SerumOrdering Guidance
This test is used for second-order testing for autoimmune thyroid disease.
For suspected cases of autoimmune hypothyroidism, the first-order testing is TPO / Thyroperoxidase Antibodies, Serum.
For suspected cases of autoimmune thyroid disease, first-order testing includes TPO and THYRO / Thyrotropin Receptor Antibody, Serum.
Specimen Required
Collection Container/Tube:
Preferred: Red top
Acceptable: Serum gel
Submission Container/Tube: Plastic vial
Specimen Volume: 0.5 mL
Collection Instructions: Centrifuge and aliquot serum into a plastic vial.
Specimen Minimum Volume
0.3 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Serum | Frozen (preferred) | 60 days | |
| Refrigerated | 7 days | ||
| Ambient | 24 hours |
Reference Values
≤1.3 TSI index
Reference values apply to all ages.
Day(s) Performed
Monday through Friday
CPT Code Information
84445
Report Available
2 to 6 daysSpecimen Retention Time
3 monthsReject Due To
| Gross hemolysis | Reject |
| Gross lipemia | OK |
| Gross icterus | OK |