Endocrine Abstracts

Introduction: The diagnosis of central hypothyroidism can be challenging and confused with other causes of low thyroxine concentrations without TSH elevation. The response of the thyroid hormone axis before and after treatment is reported in children with Central Hypothyroidism [CH] as part of an exercise aimed at validating free thyroxine reference ranges.Methods: Roche Elecsys Cobas TSH and FT4 immunoassays were used. ...

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/...