SP-D levels are increased and statistically significant in patients with lung fibrosis (p = 0.014, median of 30,178 pg/mL vs. 11,901 pg/mL in healthy controls) followed by ground-glass lesions on HRCT (p = 0.059, with a median of 16,639 pg/mL). Here, SFTPD is linked to pulmonary fibrosis.