fluctuating sweat chloride levels

F

fel

Guest
I am completely befuddled. In March one of my sons came out positive on a sweat conductivity test, so we went off to an official CF center for a sweat chloride test.

He came out 70 and 76. However, the full sequence genetics did not come out positive for any definitive mutations, so they decided to get a second sweat chloride test. It came out at 57 and 65. Based on the one arm that was below the 60 cut off, they decided to do a third sweat chloride test. That came out at 42 and 43.

Has anyone else seen such variable sweat chloride within the span of 2.5 months?

Note my other son came out as positive on 2 sweat chloride tests, but he only shows one mutation.

Fel
 
R

Ratatosk

Administrator
Staff member
How old is your child? When DS was 3 weeks old, he had a sweat test at an accredited cf center and it was a normal 32. Based on the amount of salt he sweats out today, I suspect his numbers would be very high. As for the mutations, could be a mutation that hasn't been identified yet. There are over 1500 cf mutations. The other day my niece had carrier testing done -- they only tested her for 25 of the most common mutations.
 
F

fel

Guest
My younger son with the fluctuations is 14 years old and the older son is almost 18. Also younger son has mutation S912L, which is not supposed to be disease causing on it's own.

I read somewhere that puberty can cause changes to sweat chloride. Has anyone experienced this?
 
B

Beccamom

New member
Yes, sweat test numbers can vary. I don't know how much, but a friend of mine was trying to conceive the same time my daughter's and I were being tested for CF. The ovulation test kit my friend was using used a change in salt in the sweat to determine when she was ovulating. I read on a few insurance websites that a sweat test for CF on an adult woman varies depending on the time of the month. I asked my CF doctor about that when I was tested based on time of the month I should have had my lowest numbers and he said it didn't matter since I was getting diagnosed. I don't know how that affects boys.

fel said:
My younger son with the fluctuations is 14 years old and the older son is almost 18. Also younger son has mutation S912L, which is not supposed to be disease causing on it's own.

I read somewhere that puberty can cause changes to sweat chloride. Has anyone experienced this?
Click to expand...
 
J

JustaCFmom

New member
I would love an explanation also.
I tested positive as well as one of my kids with "my" mutation and one of my kids with *no* CF mutation. All of us were over 70. I have hypothyroidism, but they are normal. The one with no mutations coughed this entire winter and apparantly has asthma. (we double checked everything and she isn't even a carrier!)
The doctor didn't really have an answer. :-(
As far as your son's levels changing, maybe he was eating a lot of salty foods?
Good luck finding answers!
 
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