Valuable hematological indicators for the diagnosis and severity assessment of Chinese children with community-acquired pneumonia: Prealbumin

Ning, Jingjing; Shao, Xiaonan; Ma, Yibo; Lv, Darong

Usually, in developed countries CAP diagnosis is mostly clinical and is confirmed by radiographic finding of consolidation. The valuable laboratory tools are also needed in the management of CAP in children, which can offer the useful clinical information on determination of appropriate treatment and courses with antibiotics based on the detected etiology agent, as well as the prognosis of the disease. PCT, a protein containing 116 amino acids, is normally produced by neuroendocrine cells in the thyroid and lungs at a very low rate and is undetectable in serum. [14] Inflammatory and infectious injuries stimulate overexpression of the CALC1 gene consequently increasing serum PCT. Under these pathologic conditions, synthesis and secretion of PCT become ubiquitous. [15] CRP is an acute phase reaction protein synthesized in the liver and is considered as a good index for early diagnosis of inflammation. [16] The usefulness of PCT and CRP in the management of pediatric CAP has been carefully studied and compared. Overall, the latest data showed that PCT was the best diagnostic marker compared to CRP, especially for the detection of pneumococcal infection. [17, 18] However, there was no significant increase of PCT and CRP in our study, which might be attributed to a low rate of bacterial infection. Actually in CAP children infected with virus and mycoplasma, PCT and CRP are not elevated or only mildly elevated. [19, 20] WBC, neutrophil percentage, neutrophil count, and ESR are the traditional indicators for screening the bacterial infections with CAP in children, but recent studies have demonstrated that the above indicators were not specific and sensitive for the diagnosis of bacterial or viral infection. [21] In this study, the above indicators were increased in the patients with CAP, but the sensitivity for diagnosis of CAP was low according to the traditional cutoff value (all P < 0.5); thus, the diagnostic value of CAP was limited. The possible reason is that the body's response to infection is poor if the child's immune system is low; thus, the above indicators might be normal. [22] PA is a carrier protein synthesized in the liver. Because PA can eliminate the toxic metabolites released during the process of infection and is gradually consumed; thus, it is a nonspecific host defense substance. Hrnciarikova et al [23] found that the elevation of serum CRP was correlated with the decrease of PA in old people with infections, suggesting that PA has the similar clinical significance with CRP. Shao et al [24] found that the PA levels were decreased in CAP group that infected with different pathogens, whereas PA reduction was more significant in bacterial infection group. Similar results were found in this study, and the sensitivity for diagnosis of CAP with traditional cutoff value was 0.847, which was significant higher than traditional inflammatory indicators. Moreover, it was found that PA was an independent protective factor for CAP in children based on multivariate analysis. It was proposed that the combination of PA with the traditional inflammatory indicators may make up the deficiency of their low sensitivity and improve the diagnostic efficacy of CAP.