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Sweat test result
- Question
- Hello,
today a sweat test has been performed to our 2 year-old son. The result has been 60 mmol/l sodium chloride.
The hospital informed us about the following interpretation:
80= pathologic
In all other publications however, other limits are mentioned:
60= pathologic
What is correct? Is there no uniform classification? We are going to do another test, but with this different classifications it seems not even possible to get a more meaningful result.....
Many thanks for your quick answer,
Yours sincerely, - Answer
- Dear questioner,
First of all it is important to know how the sweat test had been performed in order to tell you the cut-off values. The correct method is based on a chemical measurement of the sweat.
According to current consensus statements there is a uniform classification: chloride values 60 mmol/l are considered to be consistent with the diagnosis of CF.
In case the result is >60mmol/l, a second test is recommended, if the result is again >60mmol/l this confirms the diagnosis of CF.
By time, we learned, however, that there are CF-patients with even lower or even a negative sweat-test result. Therefore, if the result is borderline (40-60mmol/l), the test should be repeated; if the result is still borderline, other measures to clarify the situation are done: e.g. a mutation analysis and if needed a measurement of the potential difference of the rectum mucosa, other diagnostic tools are the analysis of the function of the pancreas (stool-fat, the pancreatic enzyme elastase in the stool), microbiological investigation of the airways. In case the sweat test shows a negative result (under 40mmol/l) further diagnostic measures should be performed if the clinical symptoms still favour the diagnosis of CF.
Due to this quite complicated situation you shoud seek for advice at a CF-centre nearby. You can get addresses at the homepage of the German patient organisation (mukoviszidose e.V. Bonn).
I hope that I have helped you further with this information.
Yours sincerely,
Dr. H.-G. Posselt - 23.04.2008
