Standardization of Steroid Hormone Assays

In this article, I will present my views on steroid hormone assay standardization, illustrated with examples from the UK National External Quality Assessment Schemes (UK NEQAS) data for oestradiol, although all the problems indicated also occur with progesterone, testosterone (especially in the female range), and, to some extent, cortisol. I will indicate where, in my opinion, effort should be directed to improve what seems to be an intractable unsatisfactory situation.