SFTPD and interstitial lung disease: Similarly, patients with CFIP (n = 19; 292.5 (32.3-1070) ng•mL−1, p < 0.0001), UCTD-ILD (n = 16; 206.0 (88.6-405) ng•mL−1, p = 0.0104), and CTD-ILD (n = 33; 175.0 (31.2-994.0) ng•mL−1, p = 0.0003) had significantly higher SP-D levels than control subjects (n = 26; 32.3 (8.6-126.0) ng•mL−1).