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Posted By : sailgirl - 5/6/2005 6:04 PM
Hi everyone,
I am wondering if anyone has any experience with a negative result from a sweat test.  From what I have read, a test is invalid if less than 75 mcl is collected.  Only 65 was collected from me and the result was 20 which is definately negative.  I am happy but puzzled because if this test is correct then that means that I am back to trying to figure out how all the puzzle pieces fit together.  If anyone has any answers I would really appreciate help.

Posted By : CF TEAM ID - 5/9/2005 2:34 PM

You should definately have another sweat done if they did not get a quanity sufficient for testing.  It is reccomended by the CF foundation that the sweat test is performed twice to confirm, especially if your do not have sufficient quanity for testing.

In additon to having another sweat test, you could have a genotype done.  Its a simple blood test that usually takes a couple of weeks to recieve results.  There are known mutations that do not produce an abnormal sweat test result, so it is possible to have a negative sweat test and still have CF.

Hopefully you do not have CF, but if you do, the sooner you can start being treated, the better you will feel.
Hope this helps..

Posted By : sailgirl - 5/10/2005 10:37 AM
CF Team,
 thank you for the reply.  I don't want to sound like a hypochondriac but I really want some answers.  I am going to my GI doc tomorrow in Houston and I will address these issues with him.  I hope that he will be open to helping me find answers, he does seem like a really nice, caring person.
Thank you,

Posted By : cfnana - 5/21/2005 9:28 PM
I've had about 4 or 5 different sweat tests, the first one was at our local hospital, it was pretty high then I had the others and they came out with different results. The one done locally was done by an inexpierienced person and ended up not being correct. However the rest of them were done by people that knew what they were doing and although they were still positive the numbers weren't as high. I don't know if that really makes a difference since I still have it but it just goes to show that you should always get another opinion. Make sure it's done at a CF center where they know what they are doing. You can get the gene testing done but not all the mutations have been found yet so you can have it without having the normal mutation. I know how frustrating it is to not know whats wrong, another thing your Dr. needs to consider is your symptons. When I was first was tested I had had pneumonia several times in my life and always had a cough, but it was my pancreatic problems that caught the attention of my lung specialist and along with the frequent lung problems he sent me for the test. I hope you don't have it but  I know you would like some answers so try to get another sweat test done, if you don't have it you'll at least be able to rule it out and you can start looking in different areas. Good Luck

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