Trying to figure out how accurate the sweat test is before tomorrow

[aleutenberg]

My son is 6 months old. Since he was born something has always felt a bit "off" for lack of a better word. His stools have always been bright green with mucus, he's had a chronic cough that is consistantly getting worse, he was always crying until about a month ago, he's always breathed funny, and he is always congested. I've been to several doctors, most of whom blew me off and told me it was a milk allergy or reflux. I tried reflux meds and a total elimination diet at first for months but neither helped. Finally I found a pediatritian who listens to my concerns. She sent me to a GI specialist who didn't feel like this was CF and kind of shot me down when I mentioned it because he's small but he was steadily gaining weight at the time. He did some blood tests and a couple of stool samples for parasites and sediment rate and concluded that he couldn't find anything wrong with him and that he was just a "fussy baby" who would grow out of it. My ped decided to send me for a sweat test anyway which we are getting tomorrow at a CF center in Chicago. My question is, he doesn't taste salty to me so does that mean the sweat test will be normal? My insurance refused to do the genetic blood panel unless his sweat test came back positive and we can't afford to pay for it out of pocket. The lab tech said it would be around 3k. I'm just concerned that the sweat test won't be accurate because he doesn't seem overly salty.

 

[Aboveallislove]

Hey Mom,
I'm so sorry for all the worry you are going through. I know there are several here who have CF who did not have a positive sweat test, but most Center's still consider it the gold standard. I'm wondering if your insurance would cover a smaller gene test to start, in which case if you they identify 1 mutation that might give grounds for them to look further. Or if they identify 1 mutation it might justify both you and your husband being tested for more to see if you are both carriers (some insurance companies cover that if the parents are of fertile age and one is a known carrier) and then you could know if there is another one your son could have. So I guess I'd just say see what happens and hopefully no matter the results you see a CF doctor after. In which case, it would make sense to ask for a throat culture and test of stool to see if there is any absorption issues. Please do let us know how it goes.

 

[aleutenberg]

Thanks, I will be sure to let you know. Do you know if not having salty skin is any indication that the sweat test will be normal?

 

[Aboveallislove]

I think that if it is really salty that would be an indicator of CF; but that if it isn't to you that may or may not show what the sweat test shows. Maybe others who have had positive ones with their little ones can chime in? DS is noticeably salty and he also had a off the charts 133 for his sweat test...so I'd imagine that some with borderline or lower positives might not be as noticeably salty. Also, have you seen your state's newborn test and what they test for? There is some level IRC or something that indicates an issue and then they test further. I'd call the newborn office and see if they can tell what they tested for and what the numbers were because if the IRC level was elevated but they only tested for 5 mutations, I'd want the CF clinic to know that. (cff.org has a link to each state and what they test for)

 

[Ratatosk]

Did they test for fat in the stools to determine pancreatic insufficiency? Have they run any throat or sputum cultures to see if he's culturing any common CF bugs such as pseudomonas or steno maltophilia or H. Flu?

DS had a normal sweat test of 32 at the age of 3 weeks -- it's difficult to get an accurate sample on teeny tiny babies -- however, blood tests showed he had one of the most common mutations. He was diagnosed prior to newborn screening due to a bowel obstruction caused by meconium ileus shortly after he was born. I do recall when he was a bit older kissing his forehead and my lips would taste VERY salty.