Sweat chloride concentrations can increase slightly with age, so there are age-related reference intervals (see Table 2 and Table 3). Sweat chloride concentrations should always be interpreted with regard to the clinical situation and the knowledge that some rare CF-causing mutations of CFTR can be associated with chloride values in the normal and intermediate ranges.
Table 2. Diagnostic interpretations for infants up to and including six months of age.Chloride Concentration
| Diagnostic Interpretation
|
≤ 29 mmol/L
| CF unlikely
|
30-59 mmol/L
| Intermediate (CF is possible)
|
≥ 60 mmol/L
| Indicative of CF
|
Table 3. Diagnostic interpretations for patients over six months of age.Chloride Concentration
| Diagnostic Interpretation
|
≤ 39 mmol/L
| CF unlikely
|
40-59 mmol/L
| Intermediate (CF is possible)
|
≥ 60 mmol/L
| Indicative of CF
|
