In another prospective pediatric study by Benito et al, of 185 patients between 2 and 14 years of age, a CRP of less than 2 mg/dL demonstrated poor sensitivity (35 percent). Prada-Arias et al found a similarly poor sensitivity (43 percent) in a prospective study of 275 admitted children.4,5 These authors did not evaluate the combination of a normal WBC and normal CRP in these studies. With regard to a combined normal WBC and normal CRP, a retrospective pediatric-only study by Buyukbese Sarsu et al found that a WBC lower than 13,100 μL and CRP less than 1.17 mg/dL still missed six out of 278 (2.1 percent) cases of acute appendicitis.6
A normal CRP alone is an inadequate test to evaluate for acute appendicitis and should not change a practitioner’s suspicion of appendicitis by itself. In cases with a normal WBC and normal CRP, the literature suggests a lower likelihood of acute appendicitis, but these results do not rule out acute appendicitis.
Dr. Jones is assistant professor of pediatric emergency medicine at the University of Kentucky in Lexington.
Dr. Cantor is professor of emergency medicine and pediatrics, director of the pediatric emergency department, and medical director of the Central New York Poison Control Center at Upstate Medical University in Syracuse, New York.
- Sengupta A, Bax G, Paterson-Brown S. White cell count and C-reactive protein measurement in patents with possible appendicitis. Ann R Coll Sure Engl. 2009;91(2):113-115.
- Vaughan-Shaw PG, Rees JR, Bell E, et al. Normal inflammatory markers in appendicitis: evidence from two independent cohort studies. JRSM Short Rep. 2011;2(5):43.
- Zouari M, Jallouli M, Louati H, et al. Predictive value of C-reactive protein, ultrasound and Alvarado score in acute appendicitis: a prospective pediatric cohort. Am J Emerg Med. 2016;34(2):189-192.
- Benito J, Acedo Y, Medrano L, et al. Usefulness of new and traditional serum biomarkers in children with suspected appendicitis. Am J Emerg Med. 2016;34(5):871-876.
- Prada-Arias M, Vázquez JL, Salgado-Barreira A, et al. Diagnostic accuracy of fibrinogen to differentiate appendicitis from nonspecific abdominal pain in children. Am J Emerg Med. 2017;35(1):66-70.
- Buyukbese Sarsu S, Sarac F. Diagnostic value of white blood cell and C-reactive protein in pediatric appendicitis. Biomed Res Int. 2016;2016:6508619.