Tandem Mass Spectrometry Improves the Accuracy of Free Thyroxine Measurements During Pregnancy

Abstract

We conclude that tandem mass spectrometry has a superior performance to immunoassay for the measurement of free thyroxine during pregnancy. Furthermore, it is ideally suited to generating trimester-specific reference intervals for free thyroxine levels. Future studies will determine if it is a better assay to use in most clinical circumstances.