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Sweat chloride

Background:

Cystic fibrosis is an inherited condition affecting approximately 1:2500 births, which is associated with increased concentration of sodium chloride in sweat.  Measurement of chloride concentration in sweat is vital in supporting a diagnosis of cystic fibrosis, and may be requested in patients with suggestive phenotype, family history or positive newborn screening test.  In most patients, a positive sweat test is diagnostic of cystic fibrosis.

In patients older than 6 months of age
Sweat Chloride Concentration Interpretation
< 40 mmol/L Negative
40 - 60 mmol/L Equivocal
> 60 mmol/L Positive

In patients younger than 6 months of age
Sweat Chloride Concentration Interpretation
< 30 mmol/L Negative
30 - 60 mmol/L Equivocal
> 60 mmol/L Positive

Reference ranges sourced from: Guidelines for the Performance of the Sweat Test for the Investigation of Cystic Fibrosis in the UK v.2 March 2014.

Other Comments:

For more information, please see the following: Sweat chloride - Lab Tests Online

About This Test

Department: Biochemistry

Requirement:

  • Sweat (Macroduct collection system)

Turnaround Time:

Within 24 hours