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Test Name:
Thyroid Stimulating Immunoglobulin

• SBMF No:
  44243
• Performance Lab Name:
  ARUP Laboratories
• Test Mnemonic:
  TSI-
• ABN:
  Not required
• CPT Code:
  84445
• LOINC Code:
  30567-2
• Ref Lab Test No:
  0099430
• Also Known As:
  TSI
• Spec Type:
  Serum
• Spec Container:
  Gold top (SST) or red top (serum) tube
• Pref Vol:
  1.0 mL
• Min Vol:
  0.7 mL
• Fasting:
  No
• Spec Collect:
  Routine venipuncture
• Spec Process:
  Clot 30 minutes
  Promptly centrifuge 15 minutes
  Immediately transfer serum to separate plastic tube and freeze
• Spec Store Transport:
  Frozen
• Spec Stability:
  After separation from cells:
  2 hours room temperature (20-30°C)
  6 days refrigerated (2-8°C)
  3 months frozen (-20°C) – Do not use frost-free units that undergo repeated freeze/thaw cycles:
• Spec Reject:
  Plasma specimen
• Methodology:
  Quantitative Bioassay
  Quantitative Chemiluminescence
• Clinical Significance:
  Refer to:
  
• Reference Range:
  

  Negative    Positive

  110% basal activity or less 111% basal activity or greater

  Interpretive Data:
  Positive results (111 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 76 mU/L may produce a weakly positive Thyroid Stimulating Immunoglobulin (TSI) result (greater than 111 percent).

• Day Run:
  Mon-Sat
• Time Reported:
  3-6 days
• Test Type:
  HORMONE