Comparison of Fresh Frozen Serum to Traditional Proficiency Testing Material in a College of American Pathologists Survey for Ferritin, Folate, and Vitamin B12

Abstract

With ferritin, proficiency survey performance of PTM is similar to that of FFS, implying that method biases relate mainly to calibration. With folate and to a lesser extent with B12, PTM and FFS exhibit different method biases, implying that the biases reflect analyte heterogeneity and/or matrix effects.