What C-reactive protein (CRP) levels are suggest appendicitis?

Updated: Jul 23, 2018
  • Author: Sandy Craig, MD; Chief Editor: Barry E Brenner, MD, PhD, FACEP  more...
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CRP levels of greater than 1 mg/dL are commonly reported in patients with appendicitis, but very high levels of CRP in patients with appendicitis indicate gangrenous evolution of the disease, especially if it is associated with leukocytosis and neutrophilia. However, CRP normalization occurs 12 hours after onset of symptoms. Several prospective studies have shown that, in adults who have had symptoms for longer than 24 hours, a normal CRP level has a negative predictive value of 97-100% for appendicitis. [3, 4, 5] Thimsen et al noted that a normal CRP level after 12 hours of symptoms was 100% predictive of benign, self-limited illness. [3]

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