Reference Values of Induced Sputum Cytology in Healthy Children in Guangzhou, Southern China

Abstract

To establish normal reference values of induced sputum cytology in healthy children in southern China. During a period from January 2010 to December 2011, a total of 580 healthy children (5-16 years of age) were approached. A total of 266 children (137 boys and 129 girls) participated in the study. Sputum induction was carried out by using 5% hypertonic saline. Cell types in the sputum were examined by using routine methods. Sputum induction was completed in 175 of the 266 subjects (65.79%), but 16 sputum samples were disqualified. The overall success rate was 59.77% (159/266). Macrophages and neutrophils were the predominant cell types: macrophages: median, 76.14%; interquartile range (IQR), 32.68%; and 2.5% to 97.5% percentile, 1.00% to 94.50%; neutrophils: median, 20.67%; IQR, 33.0%; and 2.5% to 97.5% percentile, 4.00% to 92.75%; eosinophils: median, 0.39%; IQR, 1.93%; and 2.5% to 97.5% percentile, 0.00% to 6.50%; and lymphocytes: median, 1.22%; IQR, 2.04%; and 2.5% to 97.5% percentile, 0.00% to 5.00%. The cell types did not differ among different age, gender, and passive smoking groups. Adverse events occurred in 4.4% (7/159) of the participants who completed the procedures but required no specific treatment to dissipate. Peak expiratory flow did not differ between those who completed the procedures compared with those who did not, suggesting that the procedure is safe and feasible in children. The current study represents the first attempt to develop normal reference values of induced sputum cytology in Chinese children, and could be used as a control for future studies.