2017 Consensus Criteria (Cystic Fibrosis)
Applies the 2017 Cystic Fibrosis Foundation consensus criteria.
Open the calculator → Runs in your browser. Data leaves only if you deliberately send a problem report from the interactive tool.
Example
- Positive newborn screen
- Yes
- Sweat chloride, mmol/L
- 80
Result: Cystic fibrosis criteria met
The tool opens with these values already filled in. Replace them with your own.
What the result means
- Both halves
- A diagnosis needs an entry route AND evidence of CFTR dysfunction. Neither on its own is enough.
- Entry route
- A positive newborn screen, clinical features consistent with cystic fibrosis, or a sibling with the disease.
- CFTR dysfunction
- A sweat chloride of 60 mmol/L or more, or two CF-causing CFTR variants in trans.
- 60 or more
- Consistent with cystic fibrosis.
- 30 to 59
- Intermediate. CFTR genetic analysis is needed; this neither establishes nor excludes the diagnosis.
- Under 30
- Cystic fibrosis unlikely, regardless of age.
- What 2017 changed
- The lower boundary fell from 40 to 30 mmol/L and became age-independent. A value of 35 above six months was normal before and is intermediate now.
- Why that matters
- The difference is CFTR analysis and continued follow-up rather than reassurance and discharge. Infants left intermediate after screening are designated CRMS or CFSPID and followed.
What you enter
- Positive newborn screen
- Clinical features consistent with CF
- Sibling with cystic fibrosis
- Sweat chloride, mmol/L
- Age in months
- CFTR genetic analysis
How this is calculated
Farrell PM, White TB, Ren CL, et al. Diagnosis of Cystic Fibrosis: Consensus Guidelines from the Cystic Fibrosis Foundation. J Pediatr. 2017;181S:S4-S15.e1. Read the source ↗
A reference and educational tool. Not medical, legal, or financial advice, and not a substitute for clinician judgment.