Joshua Hayden, PhD, DABCC, FAACC, is the chief of chemistry at Norton Healthcare in Louisville, Kentucky. Prior to joining Norton, he was an assistant professor of pathology at Weill Cornell Medical College and director of the toxicology and therapeutic drug monitoring laboratory at New York Presbyterian Weill Cornell Medical Center. He earned his PhD in chemistry from Carnegie Mellon University and conducted postdoctoral research at Massachusetts Institute of Technology before completing a two-year clinical chemistry fellowship at University of Washington. Joshua has special expertise developing and overseeing mass spectrometry assays in the clinical laboratory.