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congenital anomaly of the metabolic processes of an organism in which the functions and metabolism of the organism enter a state of prolonged unstable equilibrium that is expressed in unique pathological reactions and illnesses.
The inherited predisposition is actually the result of a unique accumulation through preceding generations of characteristics that occur in the organism both owing to the effect of unfavorable environmental conditions and in association with congenital anomalies of the organism’s internal environment. The mechanism of development of diathesis is closely linked with the autonomic nervous system and internal secretion. When conditions of the external environment grow worse (disruption of diet or schedule, illness of the organism) and with functional impairment of the central or autonomic nervous system, the neural regulatory mechanisms cannot ensure proper functioning by organs and proper metabolism. As a result the organism’s ability to adapt to the environment is reduced, its reactivity changes, and a predisposition to certain diseases arises. With diathesis even physiological stimuli and ordinary living conditions can cause pathological reactions and lead to illness. The predisposition to illnesses can be lessened and sometimes even eliminated.
Diathesis usually manifests itself during childhood. Sometimes constitutional anomalies can only be identified by careful investigation of the functional state of the central and autonomic nervous systems and investigation of morphological, functional, and biochemical changes in a number of systems and in the metabolism of the organism as a whole. There are different forms of diathesis. The most commonly encountered are exudative-catarrhal diathesis, lymphatic-plastic diathesis, and neural-arthritic diathesis. The manifestations of neural-arthritic diathesis change with age; in the nursing stage there is a causeless disposition to impairments of digestion and diet, increased nervous excitability, and other characteristics, while later abnormal emaciation or obesity occurs and there is vomiting during mental excitation, cardiospasm, and so on. There is no clear distinction between different forms of diathesis, and therefore they are sometimes considered variations of one diathesis that manifests itself differently depending on age. The hemorrhagic diatheses constitute a special group.