Serum procalcitonin, C-reactive protein and interleukin-6 for distinguishing bacterial and viral pneumonia in children

Pediatr Infect Dis J. 2000 Jul;19(7):598-602. doi: 10.1097/00006454-200007000-00003.


Objective: Serum procalcitonin (PCT), C-reactive protein (CRP) and interleukin-6 (IL-6) concentrations were measured in 126 children hospitalized for community-acquired, radiologically confirmed pneumonia to assess whether these host response values could be used to distinguish bacterial from viral pneumonia.

Methods: The samples for PCT, CRP and IL-6 measurements were obtained on admission or the first day of hospitalization. The etiology of pneumonia was studied with an extensive panel of methods that detected 6 bacteria and 11 viruses.

Results: In all, 54% had evidence of bacterial pneumonia, and 32% had evidence of sole viral pneumonia. In 14% of the cases the etiology could not be determined. Children with bacterial pneumonia had significantly higher PCT (median 2.09 ng/ml vs. 0.56 ng/ml, P = 0.019) and CRP concentrations (96 mg/l vs. 54 mg/l, P = 0.008) than those with sole viral etiology. However, the values markedly overlapped. No significant difference in IL-6 concentrations was seen between the two patient groups. Using PCT > or = 2.0 ng/ml, CRP > or = 150 mg/l or IL-6 > or = 40 pg/ml, the specificity was > or =80% for bacterial pneumonia. The sensitivities with these cutoff values were 50% for PCT, 31% for CRP and 34% for IL-6.

Conclusions: The results indicate that the measurement of serum PCT, CRP and IL-6 has little value in the differentiation of bacterial and viral pneumonia in children. However, in some patients with very high serum PCT, CRP or IL-6 values, bacterial pneumonia is probable.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Biomarkers / blood
  • C-Reactive Protein / analysis*
  • Calcitonin / blood*
  • Calcitonin Gene-Related Peptide
  • Child
  • Child, Preschool
  • Community-Acquired Infections / blood
  • Community-Acquired Infections / diagnosis
  • Diagnosis, Differential
  • Humans
  • Interleukin-6 / blood*
  • Pneumonia, Bacterial / blood
  • Pneumonia, Bacterial / diagnosis*
  • Pneumonia, Viral / blood
  • Pneumonia, Viral / diagnosis*
  • Protein Precursors / blood*
  • Sensitivity and Specificity


  • Biomarkers
  • CALCA protein, human
  • Interleukin-6
  • Protein Precursors
  • Calcitonin
  • C-Reactive Protein
  • Calcitonin Gene-Related Peptide