Carbohydrate Antigen 19-9 (CA19-9) Represents the Disease Activity ofNontuberculous Mycobacteria

Pulmonary MAC disease causes pulmonary involvement, such as bronchiectasis and small nodules, particularly in the middle lobe and lingular segment. An evaluation of the efficacy of pulmonary MAC disease treatment is difficult. The investigation of biomarkers against MAC infection may lead to a more precise evaluation of the treatment for MAC infection. We experienced several cases of pulmonary MAC disease and found carbohydrate antigen 19-9 (CA19-9) concentrations correlated with the activity of pulmonary MAC disease. In this study, we evaluated the role of CA19-9 as a biomarker in pulmonary MAC disease. We found an elevation of CA19-9 during pulmonary MAC disease, but not in tuberculosis, suggesting a relationship between CA19-9 and the disease activity in the elevated CA19-9 group. CA19-9 may be a promising biomarker for the evaluation of the disease activity of pulmonary MAC disease.