In an analysis that was carried out in 500,000 adults it was found that levels of bilirubin in blood were associated with a lower risk of lung cancer, chronic obstructive pulmonary disease. Bilirubin compound is produced by the breakdown of hemoglobin from red blood cells.
Serum total bilirubin is routinely measured in the primary care setting to identify hepatobiliary (liver, gall bladder and bile ducts) and blood diseases. Bilirubin may have cytoprotective (cell protective) properties, including antioxidant and anti-inflammatory effects, according to background information in the article. "Experimental studies using animal models support a protective effect of increased bilirubin against respiratory injury by environmental stressors. The epidemiological relationship between bilirubin level and the risk of respiratory disease is not well characterized," the authors write.
Laura J. Horsfall, M.Sc., of University College London, and colleagues examined the association between serum bilirubin levels and the incidence of chronic obstructive pulmonary disease (COPD), lung cancer and all-cause death in a large population-based group of patients from the United Kingdom. The study included 504,206 adults from a U.K. primary care research database (the Health Improvement Network) with levels of serum bilirubin recorded between January 1988 and December 2008.
"Based on our findings, bilirubin levels within the normal range appear to capture information about patients that may reflect a combination of environmental and genetically determined susceptibility to respiratory diseases," the authors write. "Further research is needed to investigate causal associations between bilirubin levels and respiratory outcomes. A fuller understanding of these mechanisms may lead to the potential use of targeted clinical treatments that mildly suppress UGT1A1 [liver enzyme uridine diphosphate-glucuronosyltransferase 1] activity and moderately increase bilirubin levels."