Efficacy of serum procalcitonin in evaluating severity of community-acquired pneumonia in childhood.

Microbe-specific diagnosis of community-acquired pneumonia (CAP) in childhood is difficult in clinical practice. Chest radiographs and non-specific inflammatory markers have been used to separate presumably bacterial from viral infection but the results have been inconsistent. The aim of the present study was to evaluate the usefulness of procalcitonin (PCT) in assessing the severity as well as the bacterial or viral aetiology of CAP. Serum PCT was measured by an immunoluminometric assay in 100 patients with CAP; 26 were treated as inpatients and 74 as outpatients. The pulmonary infiltrate was considered to be alveolar in 62 and interstitial in 38 cases, according to the radiological diagnosis. The bacterial and viral aetiology of pneumonia was studied by an extensive serological test panel. No differences were found in PCT concentrations between the 4 aetiological (pneumococcal, atypical bacterial, viral, unknown) and the 3 age (< 2, 2-4 and > or = 5 y) groups. Serum PCT was >0.5 ng/ml in 69%, >1.0 ng/ml in 54% and >2.0 ng/ml in 47% of all patients. PCT was higher in patients that were admitted than as outpatients (medians 17.81 vs 0.72 ng/ml, respectively, p<0.01) and higher in alveolar than in interstitial pneumonia (medians 9.43 vs 0.53 ng/ml, respectively, p<0.01). In conclusion, serum PCT values were found to be related to the severity of CAP in children even though they were not capable, at any level of serum concentration, to differentiate between bacterial and viral aetiology.