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Test Code TSI Thyroid-Stimulating Immunoglobulin (TSI), Serum

Reporting Name

Thyroid-Stimulating Immunoglob, S

Useful For

Second-order testing for autoimmune thyroid disease, including:

-Differential diagnosis of etiology of thyrotoxicosis in patients with ambiguous clinical signs or contraindicated (eg, pregnant or breast-feeding) or indeterminate thyroid radioisotope scans

-Diagnosis of clinically suspected Graves disease (eg, extrathyroidal manifestations of Graves disease: endocrine exophthalmos, pretibial myxedema, thyroid acropachy) but normal thyroid function tests

-Determining the risk of neonatal thyrotoxicosis in a fetus of a pregnant female with active or past Graves disease

-Differential diagnosis of gestational thyrotoxicosis versus first-trimester manifestation or recurrence of Graves disease

-Assessing the risk of Graves disease relapse after antithyroid drug treatment

 

A combination of TSI / Thyroid-Stimulating Immunoglobulin (TSI), Serum and THYRO / Thyrotropin Receptor Antibody, Serum is useful as an adjunct in the diagnosis of unusual cases of hypothyroidism (eg, Hashitoxicosis).

Method Name

Recombinant Bioassay

Performing Laboratory

Mayo Medical Laboratories in Rochester

Specimen Type

Serum


Specimen Required


Container/Tube:

Preferred: Red top

Acceptable: Serum gel

Specimen Volume: 0.5 mL


Specimen Minimum Volume

0.1 mL

Specimen Stability Information

Specimen Type Temperature Time
Serum Frozen (preferred) 60 days
  Refrigerated  7 days
  Ambient  24 hours

Reject Due To

Hemolysis

Mild OK; Gross reject

Lipemia

Mild OK; Gross OK

Icterus

Mild OK; Gross OK

Other

NA

Reference Values

≤1.3 TSI index

Reference values apply to all ages.

Day(s) and Time(s) Performed

Monday through Friday; 10 a.m.

CPT Code Information

84445

LOINC Code Information

Test ID Test Order Name Order LOINC Value
TSI Thyroid-Stimulating Immunoglob, S 30567-2

 

Result ID Test Result Name Result LOINC Value
8634 Thyroid-Stimulating Immunoglob, S 30567-2

Test Classification

This test has been cleared or approved by the U.S. Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.

Forms

If not ordering electronically, complete, print, and send a General Request Form (T239) with the specimen (http://www.mayomedicallaboratories.com/it-mmfiles/general-request-form.pdf).