Mass spectrometry, immunoassay and valid steroid measurements in reproductive medicine and science

Abstract

In this issue of Human Reproduction, three related Letters to the Editor appear. The first from Keelan et al. objects that testosterone measurements in cord serum reported by Liu et al. (2016) using a direct (non-extraction) testosterone immunoassay are inaccurate relative to the gold standard of mass spectrometry (MS)-based steroid measurements in cord serum, citing their thorough review of biological and analytical factors impacting on cord serum testosterone and estradiol measurement (Hollier et al., 2014). Liu et al. defend the use of a direct testosterone immunoassay with several arguments. A third letter from Warembourg et al. (2016), authors of another paper who also used a direct testosterone immunoassay for measurement in cord serum, concede that they used a convenient, available method but one which they now recognize is unsound and would no longer use. To understand why Keelan et al. are right but Liu et al. are mistaken while Warembourg et al. are on the right track, requires some background on measuring steroids in biological fluids.