TSH Receptor Antibodies (TRAb)

Chemical Pathology

Notes

• TSH receptor antibodies (TRAb) are antibodies directed against the TSH receptor and may be stimulatory or inhibitory.
• TRAb levels are primarily measured to differentiate between thyrotoxicosis with hyperthyroidism (for example, Graves' disease or toxic nodular disease) and thyrotoxicosis without hyperthyroidism (for example, transient thyroiditis).
• Measurement is also indicated in pregnant patients with a past or current history of active Graves disease, to determine the risk of neonatal thyrotoxicosis.
• The primary test for the investigation of autoimmune hypothyroidism is the detection of anti -Thyroid Peroxidase (TPO) antibodies.

Sample requirements

5 ml of blood taken into a narrow plain gold top gel tube.

Storage/transport

Send samples at ambient temperature to the laboratory on the day of collection. If unavoidable samples may be refrigerated overnight.

Required information

Relevant clinical details including reason for the request and recent TFT results.

Turnaround times

Samples are referred to an external laboratory for analysis, with results expected back within 2 weeks.

Reference ranges

<2.2 IU/L: Negative

2.2-3.3 IU/L: Equivocal

>3.3 IU/L: Positive

Further information

For further information about thyroid antibody testing see:

Lab tests online

Page updated 05/02/2025