Pediatric biomarkers in asthma: Exhaled nitric oxide, sputum eosinophils and leukotriene E4

Purpose of review Markers of disease status that provide a numerical measure of disease activity, biomarkers, have come into more routine use in medicine. This is evidenced by troponin and brain natriuretic peptide when measuring cardiac function or glomerular filtration rate in relation to kidney function. Similar markers to assess inflammation in the asthmatic lung have emerged as possible tools to guide treatment. Three biomarkers, fractional exhaled nitric oxide, sputum eosinophils and leukotriene E4 in the urine and exhaled breath condensate, have been heavily investigated. Recent findings Recent literature indicates that exhaled nitric oxide, sputum eosinophils and leukotriene E4 in the urine, and exhaled breath condensate could serve as good markers of inflammation in the asthmatic airway. These markers, when combined with conventional measures of lung function - forced expiratory flow in 1 s, peak flow or methacholine challenge - will be of benefit in improving asthma control in the pediatric population. Summary Exhaled nitric oxide and urinary leukotriene E4 are relatively easy to attain in the clinical setting. Sputum eosinophils are an excellent tool for assessing inflammation, however sputum induction can be challenging for a young child. Despite small limitations, all three biomarkers are potentially valuable when used in conjunction with conventional methods for airway control.