Please help...my 11 month old has shown several signs of CF since birth. He did not pass his meconium in the first 48hrs, he has had horrible smelling poop, he has steadily declined in weight percentiles from the 50th at birth to the 5th now, he just had a stool sample come back that said he had an "increase" in the expected level of fat in his poop. He has also has terrible problems with constipation and has been on Lactulose for months with little progress. When they did the sweat test on him when he was 6 mo it came back neg. When they did the sweat test though, they got VERY little sweat and weren't sure at first if it was enough to complete the test. After the Lab looked at it, they said it was enough but now I question if it was a reliable test. He has since been tested for everything under the sun...celiac, hypothyroidism food allergies etc. all coming back neg. We are so frustrated they are labeling him "failure to thrive" but cant seem to help us. He is a happy baby, meeting all his milestones physically...we are confused. Has anyone had a sweat test be wrong??<img src="i/expressions/face-icon-small-confused.gif" border="0">
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how reliable is the sweat test??
- Thread starter anonymous
- Start date
Emily65Roses
New member
Your worries are justified. Many many MANY people get false sweat test results. Your better bet is to demand a genetic blood test.
Sweat tests use to be the standard for CF testing. That is before they could test for the gene mutation. There is no such thing as a false Positive. Only a false Negative. When CFers are babies sometimes its hard to get an adequate amount of sweat & it happens in older CFers also. Of course making sure it gets done at an accredited center helps, but if you are in doubt I would bush for the genetic testing. It sounds like your little one is need of help & if its CF then the sooner the better!
Many many many false negative sweat tests, too many to even name on this site alone... I would either have a sweat test repeated OR as mentioned before, have a blood test for CF mutations.
Many young children, (usually under the age of 12 months) don't produce accurate sweat tests results anyways. Did you even have it done at an accredited CF center?
I would redo the sweat test and have the blood test, or both. Good lick and keep us posted.
Many young children, (usually under the age of 12 months) don't produce accurate sweat tests results anyways. Did you even have it done at an accredited CF center?
I would redo the sweat test and have the blood test, or both. Good lick and keep us posted.
I am just going to repeat what's already been said. Go for the genetic testing. Emily didn't pass her meconium and had to have surgery at two days of age. They told us at that time she probably had CF, but couldn't test her until 6 months of age, because babies didn't sweat enough. When they did test her, her sweat test came back at 103, so there really wasn't a doubt with her, but you can always get false negatives. Go for the genetic testing!
DS was born with an intestinal blockages due to meconium illeus. The did a sweat test when he was two weeks old -- he passed with 32, which is considered normal. It was done at an accredited CF clinic. Fortunately, he'd already had bloodwork at our local hospital and the genetic tests came back when he was about 5 days old for double deltaf508. Liza
thelizardqueen
New member
I'll repeat what everyone else on here has said - there is a such thing as a false negative, but not a false positive. I would have your child get a blood test done to be safe.
Thank you so much for all your input and knowledge...Of course noboby ever told us that this test could be wrong. We were sooooo nervous when we found out they wanted to test him to begin with. And then sooooo relieved when it was negative. Now I am freeked out again. I just want an answer to all this craziness. I see his doctor next week and I am definitely going to be talking to her about the genetic testing. I will keep you posted.
3timesthefun
New member
Like everyone elso said, definately ask for genetic testing. My daughters initial sweat test came back negative, and then several years later positive. One of my sons has always had a borderline sweat test. Good luck and keep us posted.
<div class="FTQUOTE"><begin quote><i>Originally posted by: <b>anonymous</b></i>
My daughter is 9 months old, and is having similar symptoms. We go in next week for a sweat test as well. I hope all goes well for you. Do you think I should just ask for genetic testing? Does it run in your family?</end quote></div>
If the sweat test comes back negative or borderline & there are enough other signs that you still seem unsure than ask for the genetic testing. CF is hereditary, but many, many people dx have no known family history of the illness. So many people are carriers & dont even know it until someone is actually born with CF!
My daughter is 9 months old, and is having similar symptoms. We go in next week for a sweat test as well. I hope all goes well for you. Do you think I should just ask for genetic testing? Does it run in your family?</end quote></div>
If the sweat test comes back negative or borderline & there are enough other signs that you still seem unsure than ask for the genetic testing. CF is hereditary, but many, many people dx have no known family history of the illness. So many people are carriers & dont even know it until someone is actually born with CF!
Ok, I have very little new to state here, everyone else has done an excellent job!!
I do just want to add in my two kids "normal" and "very near normal" sweat test results, resulting in a misdiagnosis for many years. We now know they both have two CF genes because we had the genetic testing done. For the full story click on the link to my blog.
I do just want to add in my two kids "normal" and "very near normal" sweat test results, resulting in a misdiagnosis for many years. We now know they both have two CF genes because we had the genetic testing done. For the full story click on the link to my blog.