Sweat chloride

About This Test

Department: Biochemistry

Requirement:

Sweat (Macroduct collection system)

Turnaround Time:

Within 24 hours

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