Bronchiolotis and sweat test

Question

I have a son who is 8 months old. He has been hospitalized for bronchiolitis at the age of three months and a month ago suffered a second bronchiolitis which was treated with salbutamol and fluticason. He has a permanent cough since he was born. When he was three months old he had diarrhea, which was treated with a special milk and cream – almiron pepti® mct and sinlac® cream. I think his sweat is very salty. We did the sweat test three times, two at Penteli Paediatric Hospital, where five tenths instead of the required six tenths were collected, with results 44 & 38, and one test at Aghia Sofia Hospital with a result of 30,4. I did a genetic testing at Horemio Laboratory for 95% of the CF mutations with negative results, with the exception of three changes in the gene sequence which were characterized without pathological consequences. My husband was checked at Laiko Hospital for 80% of the mutations with negative results as well. Despite all this, I am still worried, mainly due to the borderline first sweat test, but also due to the symptoms of the child. I would like to know, based on the above data, if it is possible for my child to suffer from CF, and if there is any further test we could do. Thank you in advance.

Answer

Dear friend,
You have a 8 month old baby, who has suffered two times from bronchiolitis and has symptoms from its peptic system, so you have to use a special milk and cream.
The baby has undergone three sweat tests. In order to be able to interprete the values, it is important that they have been done in an experienced center using the method of pilocarpine-ionotophoresis in order to measure the chloride concentration in the sweat. If this had been the case, the results of two of them were normal (under 40mmol/l chloride in the sweat) and the result of the other one was just borderline (40-60 mmol/l) but not pathological (over 60 mmol/l). You have been checked for 95% of the CF mutations and your husband for 80% of them with negative results for the both of you. This means that the sweat test that worries you is normal as with this constellation CF can be excluded to a very high probability.
The symptoms of your child may be attributed to other causes (e.g. a severe allergy) and not to CF.
Regarding the sweat, all sweat is salty. The sweat of the children with CF is comparatively a lot saltier than the sweat of the rest of us.
Yours friendly,
Dr. Stavros Doudounakis

04.02.2013