TSH receptor antibodies (TRAb)

What it measures

TRAb are autoantibodies that bind the TSH receptor, most often stimulating it. They confirm Graves disease and are measured in pregnancy to predict fetal or neonatal thyrotoxicosis.

Specimen and preparation

• Specimen: Serum or lithium-heparin plasma
• Tube: Gold top

Reference range

Reference ranges differ between laboratories, methods and populations. Always use the range printed on your own lab report.

Causes of high values

• Graves disease
• Graves orbitopathy
• Risk of neonatal Graves disease (maternal levels >3× upper limit)

Method

Competitive binding immunoassay (TBII) or cell-based bioassay (TSI)

Good to know

Falling levels during antithyroid drug treatment suggest a higher chance of remission.

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