POSTN and pulmonary emphysema: In our present study, no correlation was established between the plasma periostin level and measures of lung function (r = 0.086, p > 0.078), the bronchodilator response (r < 0.086, p > 0.075), however, a weak but statistically significant negative correlation with the percent of emphysema and blood neutrophil counts was found (r > − 0.101, p < 0.037).