A Medical Record Number (MRN) is a unique identifier assigned by a healthcare organization to link a patient to their clinical record within that system.
In research, MRNs may be used for prescreening, eligibility verification, and source documentation workflows, especially when studies rely on clinical care data. Because MRNs can be considered identifying information, access and use must be limited to authorized personnel and governed by privacy and security controls. Protocols and consent/authorization language should clearly describe how medical record information will be accessed and used. Proper MRN governance supports confidentiality, traceability, and accurate linkage between source data and study records.