TABLE 4.

Biomarkers in EBC in relationship with clinical studies (adapted according to reference 4).

	Comparison with healthy subjects	Correlation with	After treatment
Hydrogen peroxide
acute asthma	↑	Positive with sputum eosinophils	↓
COPD	↑	Positive with sputum neutrophils	↓
CF	↔	NA	↓
pH
acute asthma	↓	Inverse with FEV1	↑
COPD	↓	NA	↑
CF	↓	NA	↑
Bronchiectasis	↓	NA	↔
GERD	↔	NA	↔
OSA	↓	NA	NA
Adenosine
acute asthma	↑	Asthma severity, FeNO	NA
COPD	↔	NA	NA
CF	↔	NA	NA
Adenosine/urea
acute asthma	↑	NA	NA
COPD	↑	COPD severity, Inverse with FEV1	↓
CF	↑	Inverse with FEV1	↔
8-isoprostane
acute asthma	↑	NA	Resistant
COPD	↑	NA	↓
Nitrite/nitrate
acute asthma	↑	Inverse with FEV1	↓
COPD	↑	Inverse with FEV1	NA
IL-4	↑
acute asthma		NA	↓
IL-6
acute asthma	↑	NA	NA
COPD	↑	NA	NA
GER	↑	NA	NA

COPD – chronic obstructive pulmonary disease; CF – cystic fibrosis; GER – gastroesophageal reflux; GERD – gastroesophageal reflux disease; FeNO – fractional exhaled nitric oxide; FEV1 – forced exhaled volume in 1 second;↑ – increased, ↓ – decreased, ↔ – no difference, not detectable or absence; NA – not available.