etiology
Meaning of etiology: Diagnosis names what a condition is; etiology names what produced it, and the two answers can be separated by decades of research.
Definition of etiology
Etiology is the cause of a disease, and also the study of disease causes as a subject in itself. Naming the etiology means naming what actually produced the condition: an organism, an inherited change, an exposure, an injury, an immune process, or several of these acting together. It answers why this happened, which is a different question from what is happening now.
How does etiology differ from the words beside it?
| Word | Question it answers | Example, for a lung cancer |
|---|---|---|
| Etiology | What caused it | Tobacco smoke, including environmental tobacco smoke |
| Pathogenesis | How the cause produces the disease | Accumulated genetic damage and unchecked growth of one cell line |
| Diagnosis | What the condition is | Adenocarcinoma of the lung |
| Prognosis | What is likely to follow | Depends on stage and tumor biology |
Confusing etiology with pathogenesis is common, and the distinction matters because the two lead to different actions: removing a cause prevents new cases, while interrupting a mechanism treats those that already exist.
What kinds of cause are there?
Causes fall into recognizable groups: infectious, inherited, environmental or occupational, nutritional, immune, degenerative, traumatic, and iatrogenic, meaning caused by medical treatment itself. Most common long-term conditions are multifactorial, produced by an inherited susceptibility combined with exposures over time, which is why genetics rarely provides the whole answer on its own. A useful distinction separates a necessary cause, which must be present for the disease to occur, from a sufficient one, which produces it on its own. Tuberculosis cannot occur without its bacterium, yet most people who meet that bacterium never develop the disease.
What does unknown etiology mean?
It means no cause was identified despite appropriate evaluation, which is different from a cause never having been sought. The equivalent single word is idiopathic, and cryptogenic is used similarly. Neither label is permanent: stomach ulcers were long attributed to stress and acid before a bacterium was shown to cause most of them, and the reclassification changed treatment entirely. British usage spells the word aetiology.
Also known as
Used in a sentence
Further testing was ordered to help determine the etiology of the patient's persistent fever.
Good to know
A condition described as being of unknown etiology has had no cause identified despite evaluation, which is different from one whose cause has simply not been investigated.
Word origin
Where “etiology” comes from
Formed from Greek aitia, meaning cause, and -logia, meaning study of.