Thyroid Stimulating Immunoglobulin (TSH receptor antibodies)
Label Mnemonic: TSI
Epic Lab Code: LAB4165
Downtime Form: A-1a Miscellaneous Request
Commercial Mail-out Laboratory
5231 RCP
356-8593
Specimen(s):
Serum
Collection Medium:
Red top tube 5 mL (Clot Activator)
Minimum:
Preferred Minimum: 1.0 mL serum
Absolute Minimum: 0.7 mL serum
Rejection Criteria:
Plasma
Turn Around Time:
2-5 days upon receipt at reference laboratory
Reference Range:
Negative - 122% basal activity or less
Positive - 123% basal activity or greater
Interpretive Data:
Positive results (123 percent or greater) are consistent with Graves disease but do not always correlate with the presence and severity of hyperthyroidism. Antibodies to the Thyroid Stimulating Hormone Receptor (TSHR) may be stimulating, blocking, or neutral. Stimulating antibodies mimic the action of TSH and cause hyperthyroidism (Graves disease). This test determines the net effect of all TSHR antibody types present in the serum specimen.

Note: An elevated Thyroid Stimulating Hormone (TSH) value above 6 mU/L may produce a weakly positive Thyroid Stimulating Immunoglobulin (TSI) result (123 percent or greater).
Methodology:
Semi-Quantitative Bioassay/Quantitative Chemiluminescent Immunoassay
CPT Code:
84445