Discrepancy between total white blood cell counts and serum C-reactive protein levels in febrile children.

Total white blood cell (WBC) counts and serum C-reactive protein (CRP) are used as inflammatory markers in febrile children. We studied the occurrence and clinical significance of discrepancy in these markers. From a 2-y period, we retrospectively reviewed the medical records of febrile children (> or =1 month of age) with WBC > or =15 x 10(9)/l and/or CRP levels > or =80 mg/l, as well as of children with lower values in both these parameters. WBC and CRP were discordant in 556 children and concordantly high in 194 children. A severe bacterial disease was presumed in 57% of children with concordantly high WBC and CRP, in 20% of those with discordant values, and in 5% of those with low levels of these markers (p<0.001). Non-streptococcal tonsillitis was the most common viral infection associated with elevated WBC and CRP. In conclusion, WBC and CRP are commonly discrepant in febrile children. Measuring both markers increases substantially the detection rate of bacterial infections.