Thyroid-Stimulating Antibody/Thyroid-Stimulating Hormone Receptor Antibody Ratio as a Sensitive Screening Test for Active Graves' Orbitopathy.

OBJECTIVE

Graves' orbitopathy (GO), an extrathyroidal manifestation of Graves' disease, can seriously threaten a patient's quality of life. Given that immunosuppressive treatment during the early active phase of GO has been found to reduce both disease activity and severity, sensitive screening tests are needed.

METHODS

The present study included 86 patients with GO, in whom serum levels of thyroid-stimulating hormone (TSH), free triiodothyronine (T3), free thyroxine, thyroid-stimulating antibody, TSH receptor antibody, thyroid peroxidase antibody, thyroglobulin, and thyroglobulin antibody were measured within 2 months before magnetic resonance imaging (MRI) for orbit assessment.

RESULTS

The thyroid-stimulating antibody/TSH receptor antibody ratio was able to distinguish MRI results with a correct classification rate of 81%. When focusing on patients without T3 predominant Graves' diseases, the ratio distinguished MRI results at a rate of 92%. Receiver operating characteristic curve analysis revealed a cutoff antibody ratio of 87, which yielded a sensitivity, specificity, positive likelihood ratio, and negative likelihood ratio of 91%, 95%, 18.2, and 0.0957, respectively, for distinguished MRI results.

CONCLUSIONS

The thyroid-stimulating antibody/TSH receptor antibody ratio is a highly sensitive and specific indicator for active GO, especially in patients without T3 predominance, and serves as a good screening test for active GO in primary care settings.