At least 75 mg of sweat, preferably >100 mg Fridge
Sweat samples are stable for 72 hours at 4 degrees. (Biochem Med (Zagreb). 2022 Feb 15;32(1):010501. doi: 10.11613/BM.2022.010501)
Reference Intervals
Chloride less than 40
A sweat chloride concentration less than 40 mmol/L makes cystic fibrosis unlikely, although cases have been described. The likelihood of cystic fibrosis decreases with decreasing sweat chloride levels so that a sweat chloride less than 20 mmol/L makes cystic fibrosis extremely unlikely.”
Chloride 40-60
A sweat chloride concentration between 40 and 60 mmol/L is suggestive of the diagnosis of Cystic Fibrosis. Recommend CFTR mutation analysis to confirm or clarify the diagnosis.
Chloride greater than 60
A sweat chloride concentration greater than 60 mmol/L strongly supports the diagnosis of Cystic Fibrosis. Recommend CFTR mutation analysis to confirm or clarify the diagnosis.
