Methacholine challenge testing: identifying its diagnostic role, testing, coding, and reimbursement.

Methacholine challenge testing (MCT), also sometimes described as bronchoprovocation testing, is widely performed for both research and diagnostic purposes. MCT is clinically useful when the patient presents with a history of symptoms suggesting asthma, but spirometry findings are normal. Typically, MCT is performed in a pulmonary function laboratory, a clinic, or a physician's office. MCT requires time, effort, and understanding. Two standard testing regimes are identified along with proper coding and reimbursement methodologies.