Fever of Unknown Origin

Approach to the Adult Patient with Fever of Unknown Origin - Article

ABSTRACT: Fever of unknown origin (FUO) in adults is defined as a temperature higher than 38.3 degrees C (100.9 degrees F) that lasts for more than three weeks with no obvious source despite appropriate investigation. The four categories of potential etiology of FUO are classic, nosocomial, immune deficient, and human immunodeficiency virus-related. The four subgroups of the differential diagnosis of FUO are infections, malignancies, autoimmune conditions, and miscellaneous. A thorough history, physical examination, and standard laboratory testing remain the basis of the initial evaluation of the patient with FUO. Newer diagnostic modalities, including updated serology, viral cultures, computed tomography, and magnetic resonance imaging, have important roles in the assessment of these patients.

Evaluating Fever of Unidentifiable Source in Young Children - Article

ABSTRACT: Most children will have been evaluated for a febrile illness by 36 months of age. Although the majority will have a self-limited viral illness, studies done before the use of Haemophilus influenzae type b and Streptococcus pneumoniae vaccines showed that approximately 10 percent of children younger than 36 months without evident sources of fever had occult bacteremia and serious bacterial infection. More recent studies have found lower rates of bacterial infection (1.6 to 1.8 percent). Any infant younger than 29 days and any child that appears toxic should undergo a complete sepsis work-up. However, nontoxic-appearing children one to 36 months of age, who have a fever with no apparent source and who have received the appropriate vaccinations, could undergo screening laboratory analysis and be sent home with close follow-up. Empiric intramuscular antibiotics are suggested for some children; however, cerebrospinal fluid studies should be obtained first. Because immunizations have recently decreased infection rates for S. pneumoniae and H. influenzae type b, the recommendations for evaluation and treatment of febrile children are evolving and could involve fewer tests and less-presumptive treatment in the future. A cautious approach should still be taken based on the potential for adverse consequences of unrecognized and untreated serious bacterial infection.

Managing Fever Without a Source in Young Children: The Debate Continues - Editorials

Evaluation of Fever in Infants and Young Children - Article

ABSTRACT: Febrile illness in children younger than 36 months is common and has potentially serious consequences. With the widespread use of immunizations against Streptococcus pneumoniae and Haemophilus influenzae type b, the epidemiology of bacterial infections causing fever has changed. Although an extensive diagnostic evaluation is still recommended for neonates, lumbar puncture and chest radiography are no longer recommended for older children with fever but no other indications. With an increase in the incidence of urinary tract infections in children, urine testing is important in those with unexplained fever. Signs of a serious bacterial infection include cyanosis, poor peripheral circulation, petechial rash, and inconsolability. Parental and physician concern have also been validated as indications of serious illness. Rapid testing for influenza and other viruses may help reduce the need for more invasive studies. Hospitalization and antibiotics are encouraged for infants and young children who are thought to have a serious bacterial infection. Suggested empiric antibiotics include ampicillin and gentamicin for neonates; ceftriaxone and cefotaxime for young infants; and cefixime, amoxicillin, or azithromycin for older infants.

Prolonged Febrile Illness and Fever of Unknown Origin in Adults - Article

ABSTRACT: Fever of unknown origin has been described as a febrile illness (temperature of 101°F [38.3°C] or higher) for three weeks or longer without an etiology despite a one-week inpatient evaluation. A more recent qualitative definition requires only a reasonable diagnostic evaluation. Although there are more than 200 diseases in the differential diagnosis, most cases in adults are limited to several dozen possible causes. Fever of unknown origin is more often an atypical presentation of a common disease rather than an unusual disease. The most common subgroups in the differential are infection, malignancy, noninfectious inflammatory diseases, and miscellaneous. Clinicians should perform a comprehensive history and examination to look for potentially diagnostic clues to guide the initial evaluation. If there are no potentially diagnostic clues, the patient should undergo a minimum diagnostic workup, including a complete blood count, chest radiography, urinalysis and culture, electrolyte panel, liver enzymes, erythrocyte sedimentation rate, and C-reactive protein level testing. Further testing should include blood cultures, lactate dehydrogenase, creatine kinase, rheumatoid factor, and antinuclear antibodies. Human immunodeficiency virus and appropriate region-specific serologic testing (e.g., cytomegalovirus, Epstein-Barr virus, tuberculosis) and abdominal and pelvic ultrasonography or computed tomography are commonly performed. If the diagnosis remains elusive, 18F fluorodeoxyglucose positron emission tomography plus computed tomography may help guide the clinician toward tissue biopsy. Empiric antibiotics or steroids are generally discouraged in patients with fever of unknown origin.

Email Alerts

Don't miss a single issue. Sign up for the free AFP email table of contents.

Sign Up Now