An idiopathic disease is any disease with an unknown cause or mechanism of apparent spontaneous origin.
For some medical conditions, one or more causes are somewhat understood, but in a certain percentage of instances, the cause may not be readily apparent or characterized. In these cases, the origin of the condition is said to be idiopathic. With some other medical conditions, the root cause for a large percentage of all cases has not been established—for example, focal segmental glomerulosclerosis or ankylosing spondylitis; the majority of these cases are deemed idiopathic. Certain medical conditions, when idiopathic, notably some forms of epilepsy and stroke, are preferentially described by the synonymous term of cryptogenic.
Usage of synonyms
The word essential is sometimes synonymous with idiopathic (as in essential hypertension, essential thrombocythemia, and essential tremor) and the same is true of primary (as in primary biliary cholangitis, or primary amenorrhea), with the latter term being used in such cases to contrast with secondary in the sense of "secondary to [i.e., caused by] some other condition." Another, less common synonym is agnogenic (agno-, "unknown" + -gen, "cause" + -ic).
The word cryptogenic (crypto-, "hidden" + -gen, "cause" + -ic) has a sense that is synonymous with idiopathic and a sense that is contradistinguished from it. Some disease classifications prefer the use of the synonymous term cryptogenic disease as in cryptogenic stroke, and cryptogenic epilepsy.
See also
- Diagnosis of exclusion
- Embolic stroke of undetermined source
- Functional disorder
- Idiosyncratic drug reaction
- Fever of unknown origin