Asthma or CF?

Question

Dear ladies and gentlemen,
our son xaver (10 years old) has accidentally received a sweat test (pilocarpine ionotophoresis) at an asthma-control check in Wangen (Germany), the result was with 76 mmol/l NaCl borderline. At the appointment for repeating at the southclinic in Nuremberg, the result was confirmed mit 72 mmol Na Cl again. The sole chloride result was 40. For 7 years now, my son receives an asthma therapy (with former salmeterole and fluticasone), he has been on a rehab stay in Davos and to control appointments at the pulmonolgy out-patient department in Erlangen and never a sweat test had been performed for differential diagnosis. Before his asthma career, he had severe atopic eczema (from 2.5 to 3.5 years). His asthma has even improved very much in the last one and a half years, as he does not need a permanent medication anymore. The lung function tests have been always good, he did not have an asthmatic cough (no mucous congestion either) and he did not have any inflammations. The digestion has never been suspicious either. He grows slowly but continously and weighs 27kg at a heigth of 130cm.
We are of course upset, that in spite of the positive development of his asthma, now such a shadow lies over the joy about his development. We are still waiting on the result of the stool sample (pancreatic elastin) and the docotor in charge wanted to discuss the x-ray of the lung with the radiologist first, which shows ramifications (scars) in the region of the inner rims. Is it possible that the lung shows changes in spite of permanent, sucessful and continous asthma-therapy?
Our question concerning the CF, which has not been confirmed at this timepoint: can CF be in spite of a lack of symptoms and if the symptoms can occur later on and become more and more stronger. The progression is part of the illness, isn't it? We would like to be well informed and prepared, so that important therapies are not missed and he can be helped.
Suddenly we are confronted with a new illness, about which our knowledge was very small. We are very happy about this forum, as it is very informative and answers many questions.
We are looking worward to your answer

Answer

Dear questioner,
we answer today your questions from the 22 nd and 24th april.
You report, that your son has been treated for asthma for many years and that now in Wangen (Germany) a sweat test had been conducted during a rehab, which showed a "borderline result" of 72 mmol/l. A repeated control had shown a result of 70 mmol/l NaCl. The pancreatic elastase had been normal and the weight of your child is according to your information corresponding to the height.

Understandably, your are extremly upset about the severe illness, which is now under suspicion. We want to try to answer the important questions and give you advice.

In general, the picture of the illness CF can be very different and the primary appearance is in part also dependent on the respective underlying mutations of the CF-gene, that means on the individual genetic endowment. 20-25% of CF patients have no pancreatic insufficiency. Most panceras sufficient patients have a calmer course of the disease of the manifestation of the lung.

In CF-patients without having had severe problems of the lung, the first signs of CF are often changes in the thorax x-ray called an inhanced peribronchial lining. The affected patients mostly still have a normal function of the lung then, as those changes normally do not have to be regarded as severe changes of the lung structure.
From this you can recognize, that I can not give you an all-clear signal regarding the suspicion of CF. I would like to advise you to contact the nearest CF-center of your region due to a competent diagnostic. As CF specialists we are of the opinion, that in case of suspicion of asthma, a sweat test has always to be performed initially in the respective patient, in order to exclude a CF or to diagnose a CF. In the case of your son, a sweat test on both arms should be repeated as soon as possible at a CF center and if necessary then ongoing a molecular genetic investigation shoud be performed.
We wish you luck and good results for your son.
Yours sincerely,
Dr. H.-G. Posselt

15.06.2009