SFTPD and acute respiratory distress syndrome: SP-D levels in plasma were higher in cases with ARDS [median 20.8 ng/mL (IQR, 12.7–38.4); mean 27.7 ± 19.5 ng/mL] compared to their matched controls without ARDS [median 7.9 ng/mL (IQR, 4.1–17.0); mean 14.8 ± 15.5 ng/mL] (p = 0.001).