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worried mother
- Question
- My 5 year old son, already had 30 treatments with antibiotics because of repeated airway infections: upper as well as lower airways. A sweat test was done. The result was 45. The test had to be repeated; the result of the second test was 32. The upper limit of normal is 30. Still our pediatricion stated this was OK, but why is the upper limit of normal then 30?? My son thus had a borderline result tiwce. He also uses Macrogol 10 to 20 mg per day. Otherwise he cannot go to the toilet. I am really worried; can someone tell me what to do. My son coughs terrribly and is sick more or less every 6 weeks. Who has useful advice?
- Answer
- As you know, Ecorn is not a medium where we give advice about specific medical situations. We just provide answers to general questions related to CF.
The cut off values for normal and abnormal sweat test depend on which test is used. In case of a conductivity test, it is higher than in case of the classical Gibson & Cook test. In addition it is unclear whether you discuss the values for chloride or for sodium. Also the test needs to be done by a person with sufficient experience and a sufficient amount of sweat needs to be collected. So whether the result that you mention is from a valid test and whether it is normal or abnormal can thus not be stated with certainty. If a patient has symptoms that are suggestive for CF it may be indicated to repeat a sweat test. Such a test should be performed in an experienced CF center and it should measure the chloride concentration in the sweat by a so-called "pilocarpine ionotophoresis" as this is the gold-standard and conductivity measurement is not appropriate.
Of course there are many causes of coughing and airway infections in children. CF is only one of them. If a child has symptoms suggestive of CF and the sweat test is inconclusive, additional tests can be done to rule out CF. These are: measurements of the CFTR function (in the intestine by ICM = intestinal current measurement OR in the nose by NPD= nasal potential difference) or by searching for CFTR mutations by genetic testing. We thus suggest that you discuss with your doctor what the cause of coughing is in your child and whether additional tests are indicated.
We hope that this answer helps you.
Prof. Kris de Boeck
- 25.09.2012
