CALCA and idiopathic pulmonary fibrosis: LC-IPF patients with a neuroendocrine component, those with stage IV disease, and with more than two metastatic sites had significantly higher serum PCT levels in comparison to those with a non-endocrine component, stages I-III disease, and less than two metastatic sites, p = 0.001, p=0.014, and p=0.004, respectively.