However, NGAL expression did not differ markedly when comparing the COPD‐S and healthy‐S groups (11.9 versus 11.4 ng/ml, respectively; P = 0.81; P adjusted for age = 0.77; P adjusted for age and pack‐years = 0.92; Table S1). The gene discussed is LCN2; the disease is chronic obstructive pulmonary disease.