Specific biomarker levels can help differentiate children who require emergent medical interventions, such as procedures, surgeries, or antibiotics, from those who may not. Appropriate application of biomarkers after a thorough history and physical examination can potentially improve cost-effective management by minimizing unnecessary procedures and tests without sacrificing patient safety. This issue reviews the literature regarding 4 biomarkers: lactate, C-reactive protein, ferritin, and procalcitonin. Evidence-based recommendations are made for the clinical evaluation of bacterial meningitis, common infections, and appendicitis.
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4. “It doesn’t matter what my history and physical exam are. I can just order these labs and be done with it.” Biomarkers are an adjunct to the emergency clinician’s data-gathering and decision-making processes—not a replacement. Details such as duration of symptoms should factor into the clinician’s assessment and clinical gestalt. Reassessment after obtaining reassuring biomarker results is also critical.
8. “If the PCT level comes back normal in my 8-year-old patient, it will mean that I don’t need to do a lumbar puncture—even though he’s got a fever and headache.” Biomarkers must be applied appropriately. A normal serum PCT can help differentiate bacterial from viral meningitis after an LP has been performed but it cannot exclude other etiologies of headache and neck pain. This statement is an inappropriate application of PCT in this clinical setting. PCT has not currently been found to predict the need for an LP in this age group.
9. “My pediatric patient had a normal WBC and a normal CRP, so I ruled out acute appendicitis.” While a normal WBC count and CRP may rule out appendicitis in adult patients, this is not true for the pediatric population. A normal WBC count and low CRP significantly decrease the posttest probability of acute appendicitis, but it does not entirely rule out the disease in children.
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Following are the most informative references cited in this paper, as determined by the authors.
1. * Pantell RH, Roberts KB, Adams WG, et al. Evaluation and management of well-appearing febrile infants 8 to 60 days old. Pediatrics. 2021;148(2):e2021052228. (Clinical practice guideline) DOI: 10.1542/peds.2021-052228
30. * Šimundić AM. Measures of diagnostic accuracy: basic definitions. EJIFCC. 2008;19(4):203-211. (Review)
50. * Garcia S, Echevarri J, Arana-Arri E, et al. Outpatient management of children at low risk for bacterial meningitis. Emerg Med J. 2018;35(6):361-366. (Prospective; 182 patients) DOI: 10.1136/emermed-2017-206834
59. * Weiss SL, Peters MJ, Alhazzani W, et al. Surviving Sepsis Campaign international guidelines for the management of septic shock and sepsis-associated organ dysfunction in children. Pediatr Crit Care Med. 2020;21(2):e52-e106. (International guidelines) DOI: 10.1097/PCC.0000000000002198
69. * Mintegi S, Bressan S, Gomez B, et al. Accuracy of a sequential approach to identify young febrile infants at low risk for invasive bacterial infection. Emerg Med J. 2014;31(e1):e19-e24. (Retrospective; 1123 patients) DOI: 10.1136/emermed-2013-202449
70. * Gomez B, Mintegi S, Bressan S, et al. Validation of the “Step-by-Step” approach in the management of young febrile infants. Pediatrics. 2016;138(2):e20154381. (Prospective; 2185 patients) DOI: 10.1542/peds.2015-4381
72. * Kuppermann N, Dayan PS, Levine DA, et al. A clinical prediction rule to identify febrile infants 60 days and younger at low risk for serious bacterial infections. JAMA Pediatr. 2019;173(4):342-351. (Retrospective derivation and prospective; 1821 patients) DOI: 10.1001/jamapediatrics.2018.5501
88. *Huckins DS, Simon HK, Copeland K, et al. A novel biomarker panel to rule out acute appendicitis in pediatric patients with abdominal pain. Am J Emerg Med. 2013;31(9):1368-1375. (Prospective; 503 patients) DOI: 10.1016/j.ajem.2013.06.016
107. *Williams R, Mackway-Jones K. Towards evidence based emergency medicine: best BETs from the Manchester Royal Infirmary. White cell count and diagnosing appendicitis in children. Emerg Med J. 2002;19(5):428-429. (Review) DOI: 10.1136/emj.19.5.428
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Keywords: biomarker, serum biomarker, lactate, lactic acid, C-reactive protein, CRT, ferritin, procalcitonin, PCT, meningitis, bacterial meningitis, common infections, bacterial infection, invasive bacterial illness, serious bacterial infection, SBI, appendicitis
Landon A. Jones, MD
Kate Dorney, MD, MSHPEd; Jay D. Fisher, MD, FAAP, FACEP
March 2, 2022
April 1, 2025
Date of Original Release: March 1, 2022. Date of most recent review: February 5, 2022. Termination date: March 1, 2025.
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