# TRAb Test

URL: https://thethyroidologist.com/tests/trab-test/
Section: Tests
Last medically reviewed: 2025-11-01

> The TRAb test detects thyroid-stimulating immunoglobulins — the antibodies that cause Graves’ disease. When it is ordered and what results mean.

The TRAb (TSH receptor antibody) test detects antibodies that stimulate the thyroid — the specific marker for Graves’ disease, the most common cause of hyperthyroidism.
It distinguishes Graves’ from other causes of thyrotoxicosis.

## What it measures

TRAb antibodies bind to and activate the TSH receptor on thyroid cells — mimicking TSH and driving continuous hormone production. Different assays measure stimulating vs blocking antibodies.
Positive TRAb is highly specific for Graves’ disease.

## When it is ordered

TRAb is checked when hyperthyroidism is diagnosed to identify Graves’ vs toxic nodules or thyroiditis. It helps predict relapse risk after antithyroid drugs are stopped — persistent positive TRAb suggests higher relapse likelihood.
It may also be monitored in pregnancy for neonatal risk assessment.

## Interpretation

Positive TRAb confirms Graves’ disease. Negative TRAb in thyrotoxicosis suggests alternative causes — toxic nodules, thyroiditis, or factitious thyrotoxicosis.
TRAb levels correlate loosely with disease activity; very high levels may predict more severe disease or eye involvement.

## Frequently asked questions

### Can TRAb be positive without hyperthyroidism?

Yes — low-level TRAb positivity can occur in euthyroid people or during remission. Clinical context and thyroid function tests are needed.

### Does TRAb predict relapse after treatment?

Persistently positive TRAb after antithyroid drugs are stopped is associated with higher relapse risk — one factor in deciding whether to continue, switch, or stop treatment.

### Is TRAb the same as TSH?

No — TRAb is an antibody that mimics TSH’s effect; TSH is the pituitary hormone. In Graves’, TRAb drives the thyroid while TSH is suppressed.

## Disclaimer

The content on this website is for general educational purposes only and does not constitute medical advice, diagnosis, or treatment. Always consult a qualified healthcare professional about your specific condition.

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