Summary statements

• The key aspects of thyroid-related QoL are typically tiredness and emotional susceptibility, not classical depression or anxiety, and may be missed using generic PRO measures.

• A thyroid-specific instrument should be used to measure PROs.

• The selected PRO should have content validity by including the most relevant and important aspects of a concept in the context of a given measurement application.

• The selected PRO should be responsive so that it detects changes in the construct being measured over time.

• The selected PRO should be the primary study endpoint.

• The study should be adequately powered based on the primary endpoint.