Within-run CVs were testosterone using liquid chromatography-tandem mass spectrometry (LC-MS/MS). 3.0% for three levels of QC samples while between-run CVs were 27 Endocrinology/Hormones Tuesday, July 28, 9:30 am 5:00 pm of 134 samples that spanned the assay range were tested in the prototype assay and an aliquot was sent out for testing on a