Nosologie

Nosologie, from the Greek nosos meaning disease and logos meaning study, is the branch of medical science that concerns the classification, naming, and diagnosis of diseases. It aims to provide a structured framework to identify and communicate about health conditions, grouping disorders into categories based on shared features such as symptoms, etiology, pathophysiology, or prognosis. The practice encompasses nosography, the descriptive listing and naming of diseases, as well as the criteria used to determine when a set of findings constitutes a distinct disease entity.

Historically, nosology evolved from early clinical descriptions in antiquity to more systematic taxonomies in the modern era. In general medicine, international classification systems such as the International Classification of Diseases (ICD) provide standardized coding for diseases, injuries, and other health problems, with ICD-11 representing the current global standard. In psychiatry, systematic approaches to classification have emphasized patterns of course and outcome, influencing how mental disorders are defined and categorized in manuals such as the DSM series. These systems support communication, epidemiology, research, and health policy.

Key considerations in nosology include whether categories should be discrete entities or dimensional spectrums, how to handle comorbidity and diagnostic uncertainty, and how classification aligns with etiological knowledge while acknowledging social and cultural influences on disease definitions. Ongoing debates address validity, reliability, clinical utility, and the evolving nature of disease knowledge.