HI. I have a question about sweat testing. Is it possible to get a "false positive" if it wasn't done correctly? My son is 5 and has had asthma issues since about 1 year old. He has never had pneumonia, and has no stomach/bowel problems. All through his childhood his peds. have diagnosed him with allergies and asthama, a common issue in our family. However, last year at christmas his cough seemed to escalate, so just to be safe our ped had him do a sweat test. His first test was 42, so considered borderline. His next test they did on both arms, and one reading was 57 and one 62. HOWEVER the tech who did it (at our local hospital, not a CF center) left the gauze pads on for 45-50 minutes rather than the 30 specified on all the reading I have done. He forgot to come back and when he did he was very apologtic. Well, I freaked out becasue everything I have read said 60 equals a diagnosis. We went to the pulmonologist and he had his blood tested. He only tested 97 mutations, but they were all negative. So, he has concluded that Evan only has asthma and is treating him accordingly. ANyway, I can't get the nagging suspicion out of my head about CF and wondering if I am just being paranoid and that the test was wrong due to the tech. Any suggestions?
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Sweat testing
- Thread starter anonymous
- Start date
You should do a quick search on this forum for sweat tests. I've seen the same question here before and know there are plenty of well written comments on the topic.
My son's sweat test was solidly positive but it took a full-bore test from Ambry to find the rare mutation he has so I can tell you that a panel of 97 mutations is nowhere near definitive; there are something like 1100 known mutations out there.
My son's sweat test was solidly positive but it took a full-bore test from Ambry to find the rare mutation he has so I can tell you that a panel of 97 mutations is nowhere near definitive; there are something like 1100 known mutations out there.
I honestly don't know about the time to leave on gauze pads, but I have heard it said there cannot be a false positive, only a false negative. Not too sure if they didn't exacly follow protocol.
As for the testing of mutations, I would definately push for extended panel mutation. Try Quest Diagnostis, they are well known with doctors and insurance companies. But I would definatley push for that!
As for the testing of mutations, I would definately push for extended panel mutation. Try Quest Diagnostis, they are well known with doctors and insurance companies. But I would definatley push for that!
Please read my full blog -- both my kids have accurate sweat tests of 38 and 41 but we know from the extended blood work they have two CF genes. Please Please Please demand that they do a full genetic test -- we were told something VERY SIMILAR to you when our daughter was 5 years old -- it wasn't until she was 13 that someone did a full test --
I don't know if the sweat tests that you have had done are accurate or not, but the important thing is to find out for sure -- they best way to do that is demand full genetic testing.
I don't know if the sweat tests that you have had done are accurate or not, but the important thing is to find out for sure -- they best way to do that is demand full genetic testing.
Thanks to all for the replies. We actually just today got an appointment for the CF clinic in St. Louis at Cardinal Glennon Children's Hospital. They are going to repeat his sweat test, and yes I will demand exensive genetic testing. I am praying for a negative outcome, but really just want a conclusive yes or no diagnosis so we know how to treat him. If he does end up having a very mild form of CF, what is his long-term prognosis? Can I expect him to live a long and fulfilling life, or does that all depend. Thanks, just a scared momma right now.
Good luck at the clinic and here's hoping it turns out negative for CF. Prognosis for CF is highly individual even for patients with the exact same genetic mutations - heck even for identical twins with CF. But it sounds like you're a dedicated hard working mom and I think that has at least as much to do with it as anything else.
thelizardqueen
New member
Like I've always said - there is a such thing as a false negative, but not a false postive. Get a new sweat test, along with a DNA test.
At the CF walk last week I freaked out someone whose teenager daughter has asthma. We were standing around talking about newborn screening, which our state just started in January and how the two new babies at the walk were diagnosed wcf because of it.
I was talking about how fortunate we were that Max was born with a bowel obstruction because some people have a terrible time getting a diagnosis. I mentioned that Max's sweat test result was 32 -- normal; however, his blood tests showed homozygous delta f508. The daughter of this woman supposedly outgrew her asthma, but still has problems once in awhile with coughing at night, sometimes coughs up gobs of mucus. Anyway, the mom says-- omigosh, El always worries about CF and I've told her that she's fine because she's been tested, but she's only had the sweat test, never a blood test!
I was talking about how fortunate we were that Max was born with a bowel obstruction because some people have a terrible time getting a diagnosis. I mentioned that Max's sweat test result was 32 -- normal; however, his blood tests showed homozygous delta f508. The daughter of this woman supposedly outgrew her asthma, but still has problems once in awhile with coughing at night, sometimes coughs up gobs of mucus. Anyway, the mom says-- omigosh, El always worries about CF and I've told her that she's fine because she's been tested, but she's only had the sweat test, never a blood test!