Oestradiol assays: fitness for purpose?

In this review we discuss the analytical inadequacies of oestradiol assays in relation to the clinical requirements for performing them, and make recommendations for their improvement. The measurement of oestradiol can be requested in a number of clinical scenarios (precocious puberty, infertility, assisted conception, hormone replacement therapy). The very wide dynamic range of oestradiol concentrations is a huge challenge for routine assays, which they are unlikely to meet on theoretical as well as practical grounds. The EQA performance of oestradiol assays in terms of trueness, comparability, recovery and analytical sensitivity leaves much to be desired and indicates that calibration is compromised by poor analytical specificity. To make oestradiol assays fit for purpose requires concerted action by all stakeholders to define analytical quality specifications for the various clinical scenarios involved, and then to encourage concerted action by the diagnostic industry to use the steroid reference measurement system to improve specificity, trueness and traceability.