Endogenous

Endogenous, arising from a cause lying within the internal environment of the organism. The term is often used in theoretical and practical medicine to denote the starting point in the development of one or another pathological phenomenon. Thus, when speaking of an endogenous tuberculous reinfection, it is meant to indicate that the disease arose from tuberculous foci already present in the organism, rather than from the external environment; in the latter case, the reinfection would be designated as exogenous. Primarily, all hereditary ailments belong to the category of endogenous diseases. However, infectious diseases (e.g., autoinfection, the above-mentioned example with tbc) and nutritional diseases may also be endogenous, insofar as the factor determining the onset of the disease lies within one or another system of the organism. Pellagra is usually exogenous, being a product of qualitatively inadequate nutrition, but the same disease can also be endogenous, since adequate nutrition often cannot be achieved, e.g., in gastroenterostomy disease, in stenosis of the esophagus, etc. Sometimes a disease, being essentially endogenous, arises from an external cause that simulates its exogenous nature. Such are cases of traumatic diabetes, many mental diseases, etc. Ultimately, the designation of any disease as endogenous implies that its primary cause (etiology) lies within the internal environment of the organism. See also Exogenous.