Clinical Utility of C-Reactive Protein (CRP) among Pediatric Patients with Fever and Normal Leukocyte Count – a Retrospective Study

Background: The WBC count is routinely used to assess children with fever. However, the sensitivity of this test is limited. The C-reactive protein (CRP) has high sensitivity for the diagnosing of bacterial infection. However, there is a lack of information about the conditions where WBC is normal while CRP is increased. We aimed to identify the prevalence of the phenomenon and to describe its clinical features.

Methods: The study included children aged 3mo - 18 years who presented to the emergency department with fever between 2018-2020. Included were children with CRP≥15 mg/dL, a value considered highly specific for bacterial disease. Patients were divided into two groups: normal versus abnormal blood count (age-adjusted).

Results: Out of 19,790 children, 1173 were found with CRP> 15 mg/dL (5.9%). 471 (40.1%) had normal WBC. A bacterial diagnosis was determined for 74.5% of them. The duration of their fever was longer (p = 0.008), they were more of Arab/African descent (P = 0.011), had more GI symptoms (P = 0.017), and fewer of them had a fever> 39.5 degrees (P = 0.035). They had less pneumonia and UTI and more dysentery (p<0.001).

Conclusion: About 40% of patients with CRP ≥ 15 mg/dl had a normal WBC. Most of them had a bacterial infection. Children with diarrhea at presentation, fever > 2 days, Arab/African ethnicity, and fever < 39.5 were at increased risk for normal blood count, and for these cases a CRP test should be routinely considered alongside a WBC test.