Standardization of steroid immunoassays--in theory an easy task.

I deal with the process of standardization of steroid immunoassays on the basis of metrological traceability (SI units). First, I discuss the role theoretically attributed to the calibration of the measurement procedure. Since immunoassays show matrix sensitivity, I associate traceability of calibration with traceability of results pertaining to individual patient samples. From this, I stress that optimization of the immunoassays in terms of specificity and insensitivity to different kinds of interference is necessary before standardization, and that split-sample measurements should be included in the standardization process. Last but not least, I give an overview of the current status of standardization of steroid immunoassays.