Case ReportWhat Is the Therapeutic Reference Range for Levetiracetam? Grand Round/A Case StudyCouderc, Sylvain PharmD*; Chouchane, Mondher MD†; Saint-Marcoux, Franck PharmD, PhD* Author Information *Department of Pharmacology and Toxicology, CHU Limoges, Limoges; and †Department of Neuropediatrics, CHU Dijon, Dijon, France. Correspondence: Couderc Sylvain, Centre de Biologie et de Recherche en Santé, CHU Dupuytren, 22 av. Martin Luther King, 87000 Limoges, France (e-mail: [email protected]). The authors declare no conflict of interest. Therapeutic Drug Monitoring 44(3):p 363-365, June 2022. | DOI: 10.1097/FTD.0000000000000972 Buy Metrics Abstract The Therapeutic Drug Monitoring guidelines of Arbeitsgemeinschaft für Neuropsychopharmakologie und Pharmakopsychiatrie had proposed a therapeutic reference range of 10–40 mg/L for levetiracetam in 2011. In the first version of the 2017 update, it was changed to 20–40 mg/L; however, 5 months later, in an erratum version, it was changed back to 10–40 mg/L. In this study, the authors agree with the range to 10–40 mg/L but discuss to what extent a wider interval may be proposed for certain patients. Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.