What are the diagnostic criteria for cystic fibrosis (CF)?

Updated: Oct 22, 2019
  • Author: Girish D Sharma, MD, FCCP, FAAP; Chief Editor: Kenan Haver, MD  more...
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Requirements for a CF diagnosis include either positive genetic testing or positive sweat chloride test findings and 1 of the following:

  • Typical chronic obstructive pulmonary disease (COPD)

  • Documented exocrine pancreatic insufficiency

  • Positive family history (usually an affected sibling)

Parameters for the sweat chloride test are as follows:

  • The reference value is less than 40 mmol/L

  • A value higher than 60 mmol/L of chloride is consistent with CF

  • A value of 40-60 mmol/L is considered borderline, and the test must be repeated

  • In babies aged 3 months or younger, a value of 30-60 mEq/L is considered borderline and requires retesting [1]

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