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Epic Code LAB1230914 Thyroid Stimulating Immunoglobulin

Additional Codes

Beaumont Code: LAB7104

Interface Order Alias


Clinical Information

The TSH receptor (TSHR) harbors a large extracellular domain.  Patients with Graves disease commonly develop autoantibodies to epitopes present on the extracellular domain of the TSH receptor.  Such autoantibodies can be stimulatory or inhibitory in nature.  Those that are stimulatory (i.e. TSI), mimic TSH stimulation.  In contrast to TSH, thyroid stimulating immunoglobulins are not subject to a negative feedback mechanism, and thus potentiate autoimmune thyroid disease pathogenesis.  

TSI should be used as a second-order test in autoimmune thyroid disease, including:

  1. To aid in the diagnosis of thyrotoxicosis if patient has ambiguous clinical presentation or thyroid scan is indeterminate/cannot be performed.
  2. To support the diagnosis of clinically suspected Graves disease in patients with normal thyroid function tests. 
  3. As a prognostic marker for relapse of Graves disease.
  4. To predict the risk of thyroid dysfunction in a fetus of a pregnant female with active or treated Graves disease.

Collection Instructions

Container(s): Gold top (Serum Separator SST) 

Preferred Volume to Collect: 5 mL

Minimum Volume to Collect: 2 mL

Submission Container/Tube:  Plastic vial

Collection Instructions:

  • After collection, gently invert tube 8-10 times.
  • Specimen should be processed within 1 hour – See Processing Instructions below.


Processing Instructions (Laboratory, Outpatient or Off-site collection)

Processed Specimen: Serum

Centrifuge/Spin: Yes

Aliquot: Yes

Processing Instructions:

  • Allow blood to clot for 30 minutes in a vertical position and centrifuge promptly.
  • Within one hour aliquot serum into a plastic transport tube and refrigerate as soon as possible.
  • (+(1)S/PO/R)

Specimen Transport Temperature


Rejection Criteria

  • Plasma specimens.
  • Severely lipemic, icteric, or grossly hemolyzed specimens. 

Specimen Stability

Serum Specimens (Pour-Overs)

Ambient: 8 hours

Refrigerate: 7 days

Frozen: 6 months

Test Frequency

Monday – Friday.
Results available within 2 business days

Reference Range

Negative: <0.10 IU/L
Positive: >0.10 IU/L

A test cut-off of 0.55 IU/L improves the clinical sensitivity and specificity for Graves disease to 98.6% and 98.5%, respectively.  Although not common, low TSI values may be observed in patients with non-Graves thyroid disorders, or other autoimmune diseases. 

Performing Department


Performing Department Laboratory Location

Beaumont Royal Oak Special Testing Laboratory


Chemiluminescent Immunoassay



CDM Code


Epic Test ID




Reviewed Date