SFTPD and idiopathic pulmonary fibrosis: YesKL-6 and SP-D higher in aHP and cHP vs. IPD, CVD-ILD and sarcoidosisNot different in aHP vs. cHP Optimal cutoff for cHP vs. IPF:KL-6 1115 U/mL AUC 0.771SP-D 209 ng/mL AUC 0.729KL-6 and SP-D lower after 1-month steroid therapy