There were pediatric studies to suggest that FENO was significantly correlated with asthma symptoms within the past 2 weeks, dyspnea score, daily use of rescue medications, and reversibility of airflow obstruction [32], peripheral blood eosinophils, IgE, serum eosinophil cationic protein level, bronchodilator response, and FEV1 PC20 methacholine [33]; both studies could not demonstrate significant correlation with FEV1 in both liters and percent predicted. Here, IGHE is linked to asthma.