The Steroid Displacement Reagent should be used to treat appropriate samples in the following manner: add 2.5µl of SDR per 97.5µl of sample. Once the SDR has been added to the neat samples, briefly vortex the sample, incubate for 5 minutes at room temperature and then proceed with sample dilution. If you are testing a sample other than serum or plasma, treatment with SDR is not necessary. Samples that are extracted do not require treatment with SDR.