Longitudinal Correlation of Thyroid-stimulating Immunoglobulin with Clinical Activity of Disease in Thyroid-associated Orbitopathy

Purpose: To investigate the possible correlation between the changes in inflammatory active phase of thyroid-associated orbitopathy (TAO) with measured changes in thyroid-stimulating immunoglobulin (TSI) levels over time. This study was undertaken to evaluate the potential usefulness of measured TSI values in following and treating patients with TAO.

Methods: A retrospective chart analysis was performed on 23 patients who had been referred to a tertiary care oculoplastics service between July of 2002 and April of 2004 with suspected TAO. The activity status of patients with TAO was graded by using the TAO activity scale (TAOS), created to distinguish between the active and cicatricial phases of TAO. Laboratory values of TSI reported during the course of the study period were compiled for each study patient.

Results: Linear regression analysis revealed a statistical correlation between the changes in activity of TAO, as measured by the TAOS score, and changes in measured values of TSI over time. A statistically significant correlation was also found between the activity of TAO (measured by the TAOS score) and TSI value.

Conclusions: It was found that changes in inflammatory phase of TAO, as measured by the TAOS score, statistically correlate with changes in measured TSI. An additional correlation was also found between the absolute score of TAO activity and measured level of TSI. These findings suggest that serial TSI measurements may be an adjunct in assessing clinical inflammatory activity of TAO and may help direct clinical decision making regarding treatment decisions in TAO.