cryptogenic

Cryptogenic is a medical adjective used to describe a disease or condition whose cause remains unknown after appropriate evaluation. The term derives from the Greek kryptos “hidden” and genesis “origin.” It is widely used across medical fields but is especially common in neurology and hepatology.

In neurology, cryptogenic stroke refers to an ischemic stroke for which no source of embolism or other cause is identified after comprehensive assessment, including brain and vascular imaging, echocardiography, and extended cardiac rhythm monitoring. The TOAST classification designates a substantial subset as undetermined or cryptogenic. Prolonged rhythm monitoring and advanced imaging have reduced the proportion over time as occult sources are detected, but cryptogenic strokes remain a meaningful clinical category in guidelines. Management focuses on general secondary prevention and individualized risk assessment, with ongoing research into occult arrhythmias and other mechanisms to reclassify strokes.

In hepatology, cryptogenic cirrhosis is used when cirrhosis has no identifiable cause after evaluation. The term also appears in discussions of cryptogenic liver disease more broadly, where metabolic risk factors such as nonalcoholic fatty liver disease are increasingly recognized as contributors, yet some cases remain unexplained after standard workups.

The term is used defensively to denote uncertainty and may be revised as diagnostic capabilities improve, including genetic testing and improved imaging. It is not a diagnosis so much as a placeholder indicating unknown etiology until further evidence emerges.