symptom(redirected from Rational symptom)
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an indication of a phenomenon, for example, of a disease. Many types of symptoms are distinguished in medicine. Constitutional symptoms characterize diseases of varying genesis and include weakness and increases in body temperature. Pathognomonic symptoms indicate a definite nosologic form; a stabbing pain in the epigastric region, for example, is typical of a perforating gastric ulcer. Subjective symptoms are only revealed upon questioning the individual, and objective symptoms are readily observable through examination, palpation, percussion, auscultation, and laboratory and instrumental diagnostic methods. Signal symptoms are the precursors of a disease. They include early symptoms, such as chest pains with pneumonia, and late symptoms, such as peritoneal irritation with cholecystitis.
A disease is said to be atypical if its characteristic symptoms are absent from the very beginning; an example of an atypical disease is the painless form of myocardial infarction. Modern therapeutic measures and protective inoculations can substantially alter the symptoms of a disease and even cause them to disappear. Diagnosis and prognosis are based on a knowledge of all of the symptoms of a disease.