The amount of bilirubin in the blood might predict the progression of idiopathic pulmonary fibrosis (IPF), according to a recent study. If validated in larger studies, bilirubin levels in the blood — or serum bilirubin — could offer a cheaper, simpler, and more convenient blood test than other prognostic markers of IPF. The study, “Correlation between serum bilirubin levels and the severity as well as the prognosis of idiopathic pulmonary fibrosis,” was published in the journal Chronic Respiratory Disease. A link between serum bilirubin and pulmonary diseases — such as chronic obstructive pulmonary disease, asthma, and lung cancer — has been reported. However, it is not clear if a link also exists between serum bilirubin levels and IPF.