INTRODUCTION
Fever is the abnormal elevation of body temperature. It is a nonspecific sign of disease. The significance of fever lies in its indication of disease processes. Fever is defined as a core body temperature ≥38.0°C (100.4 °F). However, the clinically relevant defined cutoff point of an abnormally elevated temperature is based on a particular child’s risk for infection. Fever in neonates or in immunocompromised patients is defined as ≥38.0°C (100.4°F) and in older children as ≥38.5°C (101 °F) to 39.0°C (102°F).
Body temperature is usually measured by rectal thermometry in infants and young children and by sublingual thermometry in older children and adolescents. Because temperature may vary in different areas of the body, tympanic, temporal artery, and pacifier thermometers may not correlate with rectal measurements in young children.
Because fever is an indication of disease, the most important management and therapeutic measures are to determine the underlying cause of the fever (e.g., infection, inflammation, neoplasm). When the underlying disease is treated appropriately, the fever can be managed with antipyretics as needed to make the child comfortable.
DIFFERENTIAL DIAGNOSIS LIST
Infectious Causes
Systemic
Sepsis
Occult bacteremia
Viral syndrome
Tick-borne infections (Lyme disease, Rocky Mountain spotted fever)
CNS
Meningitis
Encephalitis
Respiratory Tract
Upper respiratory tract infection
Pharyngitis/tonsillitis
Retropharyngeal abscess
Otitis media
Croup
Sinusitis
Pneumonia
Bronchiolitis
Abdominal/Pelvic
Gastroenteritis
Appendicitis
Genitourinary
Urinary tract disease
Pelvic inflammatory disease
Tubo-ovarian abscess
Musculoskeletal
Osteomyelitis
Septic arthritis
Cutaneous
Cellulitis
Abscess
Toxicologic Causes
Salicylates
Cocaine
Amphetamine
Anticholinergics
Malignant hyperthermia
Neoplastic Causes
Leukemia
Lymphoma
Inflammatory Causes
Acute rheumatic fever
Systemic lupus erythematosus
Juvenile rheumatoid arthritis
Kawasaki disease
Inflammatory bowel disease
Serum sickness
Drug and immunization reactions
Miscellaneous Causes
Heat stroke
Thyrotoxicosis
Dehydration
Prolonged seizures
Factitious
EVALUATION OF COMMON PRESENTATIONS
Infants Less Than 2 Months of Age
Well-appearing infants (0 to 60 days of age) with a fever (≥38.0°C [100.4°F]) but without an identifiable source of infection are at risk for occult serious bacterial infections. These young infants may have only vague or nonspecific signs and symptoms of illness that do not indicate the severity of potential infection.
Physical Examination
Physical examination should concentrate on identifying infections that are more common in neonates, such as meningitis, herpes simplex virus encephalitis, omphalitis, pneumonia, bronchiolitis and pyelonephritis.
