Sweat test in case of food intolerance and atopic dermatits

Question

Hello,
my daughter has had a sweat test last week. The result was at 32.
Is that still in the normal range? I have to mention, that she has an atopic dermatitis and a food intolerance. Cow's milk (step 3), chicken egg (step 4) and peanuts (step 3).

Answer

Dear questioner,
many thanks for your question.
A sweat test result between 30-59 is in the borderline range.
It has to be emphazised, that the sweat test has to be done at an experienced center according to the guidelines: via the so-called "pilocarpine ionotophoresis" the chloride concentration in the sweat is measured.
In case of atopic dermatitis it can be the case, that a false positive sweat test occurs. For this reason, the test should be done only on healthy skin areas. The guildelines [German](www.awmf.org/uploads/tx_szleitlinien/026-023lS_2k_Diagnose_der_Mukoviszidose_2013-07.pdf ) on the topic diagnosis of CF recommend in case of atopic dermatitis to repeat the measurement after optimizing the skin and weight conditions.
It would be important to know, if there are clinical (development of weight, BMI percentile, stool changes, symptoms of the airways) or diagnostic hints (newborn screening, siblings with CF). Furthermore it would be important to know, if the skin was healthy. This, you should discuss with your CF center.
Probably it would make sense, to advise you after a new sweat test on healthy skin and proabaly after improving the weight situation.
Best regards
PD Dr. Sabina Schmitt-Grohé

19.01.2016