[Fever of unknown origin. Pathogenesis and diagnostic procedure]

Patients with fever, either intermittent or continuous over three weeks or more, and which is still undiagnosed after one week's hospitalization, constitute a classic medical problem. According to recent literature a "common pathway" for the fever pathogenesis is described: Leukocytic pyrogen increase the formation of arachidonic acid which in their turn increase the formation of prostaglandin E, which then affects the thermoregulatory center. Some procedures for diagnostic investigation of the numerous complaints with this symptom in common are presented in a diagrammatic form. Patients who remain without a diagnosis must be kept under close observation. Attempts at treatment for diagnostic purposes should be avoided.