- Diagnosis of Cystic Fibrosis (CF) as determined by the 2008 CF Consensus Conference criteria: Sweat chloride level ≥ 60 milliequivalents per liter (mEq/L) by quantitative pilocarpine iontophoresis; or a genotype with 2 identifiable mutations consistent with CF; or an abnormal nasal transepithelial potential difference (NPD), and 1 or more clinical features consistent with CF