TY - CHAP M1 - Book, Section TI - Novel Approaches to Diseases of Unknown Etiology A1 - Adams, David A1 - Toro, Camilo A1 - Loscalzo, Joseph A2 - Loscalzo, Joseph A2 - Fauci, Anthony A2 - Kasper, Dennis A2 - Hauser, Stephen A2 - Longo, Dan A2 - Jameson, J. Larry Y1 - 2022 N1 - T2 - Harrison's Principles of Internal Medicine, 21e AB - The term disease, etymologically meaning “lack of ease” or the presence of discomfort, is defined as an abnormal state that negatively affects the structure or function of all or part of an organism and that is not due to any immediate external injury. When referring to a person experiencing a disease, the word patient is used in its original, meaning “the one who endures suffering.” These terms are well suited when referring to patients with undiagnosed diseases. A patient with an undiagnosed disease is one for whom a medical diagnosis is not discerned after reasonable efforts utilizing established methods and procedures. Multiple factors may contribute to a failure to reach a diagnosis (Table 492-1). Patients who are affected by an undiagnosed disease for a protracted period of time can be said to be in an undiagnosed disease state. SN - PB - McGraw-Hill Education CY - New York, NY Y2 - 2024/03/28 UR - accessmedicine.mhmedical.com/content.aspx?aid=1190514144 ER -