Serum procalcitonin concentrations in bacterial pneumonia in children: a negative result in primary healthcare settings.

A microbe-specific diagnosis in community-acquired pneumonia (CAP) is difficult in children, and studies on nonspecific chest radiographic and host response markers have been inconsistent. Serum procalcitonin (PCT) is a newly recognized, promising marker for differentiating between bacterial and viral infections. Serum PCT was measured by a luminometric assay in 190 children with CAP diagnosed in the primary healthcare setting during a population-based study in a geographically defined population. The pneumococcal, mycoplasma, chlamydia, and viral etiology of infections was studied by an extensive serologic test panel. The median PCT concentrations were 0.47, 0.46, and 0.35 ng/mL in children aged <5 years, 5-9 years, and >/=10 years (P = 0.004). An elevated PCT >1.0 ng/mL was seen in 12.1% and >2.0 ng/mL in only 2.1% of the children. No association was seen between severity (inpatient vs. outpatient care) and etiology of CAP (evidence for pneumococcal, mycoplasma, or chlamydia, vs. viral infection). We conclude that serum PCT measurements have no role in the diagnosis of bacterial CAP in children in primary healthcare settings.