An extensive bundle of tests is needed to detect treatable causes of bronchiectasis (Bx)

International guidelines suggest a limited bundle of tests to investigate Bx etiology. We aimed to evaluate an extensive bundle performed on every patient to increase the chances to identify a treatable etiology. A prospective, observational study was conducted at Policlinico Hospital in Milan, Italy, from 2014 to 2017. All consecutive adults with Bx underwent the following tests: CBC, Aspergillus IgG and IgE, serum electrophoresis, sweat test and genetics for cystic fibrosis, immunoglobulins, IgG subclasses, lymphocytes subsets, nasal NO, autoantibodies, serum level and genetics for alpha1-antitrypsin deficiency (AATD). Bx etiologies identified based on the results of this extensive bundle were compared to etiologies identified based on the results of tests suggested by the BTS 2010 guidelines. Treatable etiologies were considered according to Lonni (Ann Am Thorac Soc 2015).