Sweat test

Question

Dear expert team,
Our son (14 months-old) has already had 2 sweat tests, the first one due to an obstructive bronchitis at the age of 3 months and the second one has been repeated as he had been in the university hospital due to an unclear obstipation at the age of 6 months (this obstipation was quickly over after a bit of changing the food). Both tests had been negative and were also clearly under the "greyzone", so that we have been told, everything was o.k. About 6 weeks ago he got an infection from the Kindergarten and he coughs since then. Not very strong and also often rather dry, but however continously and our pediatrician said that this was rather a dry cough and the lung would also be mostly free. He said also, that I should definitely forget about the topic CF after 2 negative sweat tests, I however am worried because of the persistent cough and the prehistory. Furthermore, I stated today that his weight is nearly on the same level for 3 months (only 100g more), he has however been a really big baby and has been on the 97. percentile until the U6, so that he gets a normal figure now. His digestion is mostly normal, he only has to fight often flatulences. Under these circumstances should I ask the pediatrician in spite of his doubts for a third sweat test or another further diagnostic or would this be exaggerated?

Answer

Hello,
you report, that your now 14 months-old son has had 2 swaet tests at the age of 3 and 6 months, at first time because of an obstructive bronchitis and at the second time because of an obstipation. Both results were clearly below the limit in the negative area. As your son shows now anew a light, dry cough for 6 weeks and as your son did gain only a little weight in the last 3 months, you are worried and ask if the test should be again repeated.
We do not have any information in which hospital or department the sweat test had been performed and how close together both values were. In case the tests had been performed at a CF-center then you can for sure rely on the result. An a bit more persistent tendency to cough of a child who tends probably a bit more to obstructive bronchitis, does not seem worrying to me, as the child is in the kindergarten in daily contact to children of the same age, who also have frequent infections in this part of the year. It is normal, that your child does not gain too much weight at the moment. Due to the increased physical activity and with trials to walk etc. children elongate at this age and reduce perhaps their first baby fat.
Therefore, in case the sweat test had been performed by an experienced hospital you can calmly rely on them.
I wish you and your son all the best.
Yours sincerely,
Dr. H.-G. Posselt

22.04.2013