Relapse Versus Rebound in Thyroid Eye Disease After Teprotumumab Treatment: A Retrospective Case Series

Thyroid eye disease relapse after teprotumumab differs by disease phase at initiation. Active phase patients experience earlier, more prolonged, and more severe relapses, suggesting teprotumumab acts as a disease modulator. Stable phase patients exhibit shorter, nonprogressive symptom return, which we would term "rebound"-suggesting a distinct mechanism. These findings underscore the need for phase-specific counseling, monitoring, and further investigation into potentially disparate mechanisms of action of teprotumumab in the acute and stable phases.