Endocrine Abstracts

Introduction: Free thyroxine (FT4) assays are available on different commercial platforms where manufacturers provide different reference ranges. The lower limit of normal varies considerably between 8 and 13.9 pmol/l depending on the FT4 assay being used. There is concern about the validity of these reference ranges in paediatric populations, especially for the Roche FT4 assay; here there is a tendency for FT4 results to be below age-related lower limits of 13.9 or 13.6 pmol/...