Virginia Commonwealth University School of Medicine 1 article published in JoVE Biochemistry Detection and Quantification of Calcitonin Gene-Related Peptide (CGRP) in Human Plasma Using a Modified Enzyme-Linked Immunosorbent Assay Pavan S. Krishnan1,2, Fernando T. Zamuner1,3, Carolyn M. Jenks1, Johnny Y. Xie4, Lisa Zhang5, Mohammed Lehar1, Neal S. Fedarko6, Mariana Brait1,3, John P. Carey1 1Department of Otolaryngology-Head & Neck Surgery, Johns Hopkins University School of Medicine, 2Virginia Commonwealth University School of Medicine, 3Department of Oncology, The Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, 4Department of Otolaryngology-Head and Neck Surgery, University of Michigan Medical School, 5Department of Otolaryngology-Head and Neck Surgery, The Ohio State University College of Medicine, 6ICTR Clinical Research Core Laboratory, Johns Hopkins University School of Medicine Published data pertaining to calcitonin gene-related peptide (CGRP) concentrations in human plasma are inconsistent. These inconsistencies may be due to the lack of a standardized, validated methodology to quantify this neuropeptide. Here, we describe a validated enzyme-linked immunosorbent assay (ELISA) protocol to purify and quantify CGRP in human plasma.