pediatrics
Fever in Infants and Children
Testing for Chronic Fever
For chronic fever (fever of unknown origin [FUO]), laboratory tests and imaging should be directed toward likely causes of fever based on the patient's age and findings from the history and physical examination. Indiscriminate ordering of laboratory tests is unlikely to be helpful and can be harmful (ie, because of adverse effects of unnecessary confirmatory testing of false positives). The pace of the evaluation is dictated by the appearance of the child. The pace should be rapid if the child is ill-appearing, but can be more deliberate if the child appears well. All children with FUO should have Complete blood count with manual differential Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) Blood cultures Urinalysis and urine culture Chest x-ray Serum electrolytes, bloodureanitrogen (BUN), creatinine,albumin, and hepatic enzymes HIV serology Tuberculin skin test or interferon-gamma release assay The results of these studies in conjunction with findings from the history and physical examination can focus further diagnostic tests. /L) have a higher risk of serious bacterial infection. If atypical lymphocytes are present, a viral infection is likely. Immature WBCs should prompt further Diagnosis . Eosinophilia may be a clue to parasitic, fungal, neoplastic, allergic, or immunodeficiency disorders. The ESR and CRP are nonspecific acute-phase reactants that are general indicators of inflammation; an elevated ESR or CRP makes factitious fever less likely. A normal ESR or CRP can slow the pace of the evaluation. However, ESR or CRP may be normal in noninflammatory causes of FUO ( see Table: Some Causes of Fever of Unknown Origin (FUO) ). Blood cultures should be done in all patients with FUO at least once and more often if suspicion of serious bacterial infection is high. Three blood cultures should be done over 24 hours in patients who have any manifestations of infective endocarditis. A positive blood culture, particularly forS. aureus, should raise suspicion for occult skeletal or visceral infection or endocarditis and lead to performance of a bone scan and/or echocardiography. Urinalysis and urine culture are important because UTI is among the most frequent causes of FUO in children. Patients with FUO should have a chest x-ray to check for infiltrates and lymphadenopathy even if lung examination is normal. Serum electrolytes, BUN, creatinine, and hepatic enzymes are measured to check for renal or hepatic involvement. HIV-specific tests and Other tests are done selectively based on findings: Stool testing Bone marrow examination Serologic testing for specific infections Testing for connective tissue and immunodeficiency disorders Imaging Stool cultures or examination for ova and parasites may be warranted in patients with loose stools or recent travel.Salmonellaenteritis can infrequently manifest as FUO without diarrhea. Bone marrow examination in children is most useful in diagnosing cancer (especially leukemia) or other hematologic disorders (eg, hemophagocytic disease) and may be warranted in children with otherwise unexplained hepatosplenomegaly, lymphadenopathy, or cytopenias. Serologic testing that may be warranted, depending on the case, includes but is not limited to Epstein-Barr virus infection, cytomegalovirus infection, toxoplasmosis, bartonellosis (cat-scratch disease), syphilis, and certain fungal or parasitic infections. An antinuclear antibody (ANA) test should be done in children > 5 years with a strong family history of rheumatologic disease. A positive ANA test suggests an underlying connective tissue disorder, particularly systemic lupus erythematosus. Immunoglobulin levels (IgG, IgA, and IgM) should be measured in children with a negative initial evaluation. Low levels may indicate an immunodeficiency. Elevated levels can occur in chronic infection or an autoimmune disorder. Imaging of the nasal sinuses, mastoids, and gastrointestinal tract should be done initially only when children have symptoms or signs related to those areas but may be warranted in children in whom FUO remains undiagnosed after initial testing. Children with elevated ESR or CRP, anorexia, and weight loss should have Diagnosis , particularly if they also have abdominal complaints with or without anemia. However, imaging of the gastrointestinal tract should be done eventually in children whose fevers persist without other explanation and may be caused by disorders such as psoas abscess or cat-scratch disease. Ultrasonography, CT, and MRI can be useful in evaluating the abdomen and can detect abscesses, tumors, and lymphadenopathy. Imaging of the central nervous system is generally not helpful in the evaluation of children with FUO. However, lumbar puncture may be warranted in children with persistent headache, neurologic signs, or an indwelling ventriculoperitoneal shunt. Other imaging techniques, including bone scan or tagged WBC scan, can be helpful in selected children whose fevers persist without other explanation when suspicion for a source that could be detected by these tests exists. Ophthalmologic examination by slit lamp is useful in some patients with FUO to look for uveitis (eg, as occurs in juvenile idiopathic arthritis) or leukemic infiltration. Biopsy (eg, of lymph nodes or liver) should be reserved for children with evidence of involvement of specific organs. Empiric treatment with anti-inflammatory drugs or antibiotics should not be used as a diagnostic measure except when juvenile idiopathic arthritis is suspected; in such cases, a trial of nonsteroidal anti-inflammatory drug (NSAIDs) is the recommended first-line therapy. Response to anti-inflammatory drugs or antibiotics does not help distinguish infectious from noninfectious causes. Also, antibiotics can cause false-negative cultures and mask or delay the diagnosis of important infections (eg, meningitis, parameningeal infection, endocarditis, osteomyelitis). 