HESI DART Committee Thyroid Hormone Assessment Workshop

Recent updates to OECD developmental/reproductive toxicology guidelines and other regulatory guidelines and guidance require the measurement of thyroid hormone levels in the blood of mammalian laboratory species during development.  Preliminary analyses indicate that there is a wide variability across laboratories in the methods being used to measure thyroid hormones in young rodents, as well as in the success of obtaining reliable data.  Even though publicly available regulatory guidelines and guidance address study design, they allow varied approaches to thyroid hormone measurement in rodents, and an optimal study design or logical approach to thyroid hormone testing in young rodents has not yet been established in a regulatory testing context.  Validity, accuracy, sensitivity and reproducibility of the assays are issues of concern.  It is not clear to what extent variability in the data can be attributed to methodological issues or to innate biological variability.

WORKSHOP AIMS

1. Present the state-of-the-science on thyroid hormone assessments, specifically as it relates to preclinical methods and data collection, and identify gaps and knowledge as it relates to regulatory DART testing,
2. Provide clarification and guidance regarding the collection (timing and methods), assessment (standardization and validation), and interpretation of thyroid hormone data (as it relates to adversity) for regulatory toxicology and risk assessment,
3. Discuss and come to consensus on recommendations on how to improve data interpretation/understanding of thyroid changes and their relationship to adverse outcomes