Nosology

Nosology (from the Greek νόσος, nosos, "disease" + λόγος "logos") is a branch of medicine that deals with classification of diseases.

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).

One of the earliest efforts at developing a classification of diseases began in the 10th century, when the Arabian psychologist Najab ud-din Unhammad classified a nosology of nine major categories of mental disorders, which included 30 different mental illnesses in total. Some of the categories he described included obsessive-compulsive disorders, delusional disorders, degenerative diseases, involutional melancholia, and states of abnormal excitement.

In the 18th century, the taxonomist Carolus Linnaeus, Francois Boissier de Sauvages, and psychiatrist Phillipe Pinel developed an early classification of physical illnesses. Thomas Sydenham's work in the late 17th century might also be considered a nosology. In the 19th century, Emil Kraepelin and then Jacques Bertillon developed their own nosologies. Bertillon's work, classifying causes of death, was a precursor of the modern code system, the International Classification of Diseases.

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.

See also

• Clinical coder
• Differential diagnosis
• International Statistical Classification of Diseases and Related Health Problems
• Medical classification
• Pathology (study of disease)
• Category:Diseases and disorders (Wikipedia's categorization of diseases)
• ICD-10 International Statistical Classification of Diseases and Related Health Problems 10th Revision

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

• Nosology.net: An online resource for nosologic diagnostic systems. This site also demonstrates how the proposed system can be used currently in Neurology and Psychiatry