Fever in Children

Abstract

Fever is the most common presenting complaints in pediatric practice, accounting for 10% to 20% of office and emergency room visits. Pathophysiology of Fever Three pathophysiologic bases exist for fever. The first involves the raising of the hypothalamic set point in the central nervous system. Infection, collagen vascular disease, and malignancies are most commonly responsible. This type of fever is lowered by antipyretics and physical removal of heat. A second type of fever is a result of heat production exceeding heat loss as, for example, in salicylate overdose, hyperthryroidism, excessive environmental temperature, and malignant hyperthermia. The third type of fever is caused by defective heat loss, as seen with ectodermal dysplasia, heat stroke, and poisoning via anticholinergic drugs. Antipyretics are ineffective for the second and third types of fever. Biologic Process of Fever Reduction Fever occurs as a result of a number of complex biologic interactions. Exogenous pyrogens, including viruses, bacteria, fungi, antigen-antibody complexes, and drugs, are engulfed by phagocytic leukocytes, leading to the production of an endogenous pyrogen called interleukin-1 (Fig. 1). This compound (also known as lymphocyte-activating factor), in conjunction with interleukin-2, is responsible for increasing the number of helper T cells and initiating the production of prostaglandins in the hypothalamus. Helper T cells are instrumental in fighting infections; prostaglandins are responsible for producing fever.