Diseases may be classified by etiology (cause), pathogenesis (mechanism by which the disease is caused), or by symptom(s). Alternatively, diseases may be classified according to the organ system involved, though this is often complicated since many diseases affect more than one organ.
A chief difficulty in nosology is that diseases often cannot be defined and classified clearly, especially when etiology or pathogenesis are unknown. Thus diagnostic terms often only reflect a symptom or set of symptoms (syndrome).
The early nosological efforts grouped diseases by their symptoms, whereas modern systems (e.g. SNOMED) focus on grouping diseases by the anatomy and etiology involved.
^ Millon, Theodore (2004), Masters of the Mind: Exploring the Story of Mental Illness from Ancient Times to the New Millennium, John Wiley & Sons, p. 38, ISBN 0471679615
External links
Gordon L. Snider, Nosology for Our Day Its Application to Chronic Obstructive Pulmonary Disease, American Journal of Respiratory and Critical Care Medicine Vol 167. pp. 678-683, (2003). fulltext