Serum periostin levels were significantly higher in patients with mild to moderate asthma (P = 0.01), Th2-high (P = 0.029), high peripheral blood eosinophil counts (≥ 0.14 × 109 cells/L) (P = 0.01), and high FeNO levels (≥ 50 ppb) (P < 0.001) [Fig. 1a and Additional file 2: Table S2]. Here, POSTN is linked to asthma.