Soluble urokinase plasminogen activator receptor: an indicator of pneumonia severity in children

Enhanced level of soluble urokinase plasminogen activator receptor (suPAR) level has been associated with activation of the immune system. It may be a novel biomarker for pneumonia severity, yet data on this subject are limited. In the present study we seek to determine the suPAR level in hospitalized children with community-acquired pneumonia (CAP), its correlation with pneumonia severity, and to compare the suPAR level between pneumonia and healthy conditions. The study encompassed a total of 596 children: 447 with pneumonia and 119 healthy. suPAR was measured in 227 out of the 447 pneumonia patients and in all healthy subjects. We used clinical indicators (fever, time for defeverscence, heart and breath rate, saturation, and length of antibiotic treatment and of hospitalization) and laboratory indicators (CRP, procalcitonin, white blood cell count, and sodium) to assess the CAP severity. The finding were that the suPAR concentration in children with pneumonia was significantly higher (median 7.11 ng/mL) than in healthy individuals (4.68 ng/mL). We found a positive correlation between the suPAR and the following factors: fever, time for defeverscence, length of hospital stay, and elevated CRP and procalcitonin levels. There was a reverse correlation with sodium concentration and capillary blood saturation. Moreover, the suPAR level was significantly higher in children with a severe course of pneumonia compared with those having non-severe pneumonia (7.79 vs. 6.87 ng/mL; p = 0.006). In conclusion, suPAR elevation is observed in pneumonia and may reflect its severity.