- [voiceover] the goldstandard for diagnosing cystic fibrosis is called the sweat test. now it's not where you have to exercise a lot and sweat a lot,but the sweat is used to analyze how much chloride is in there. so the point of this wholetest is how much chloride. and an abnormally high chloridepoints to cystic fibrosis. a lot of times this test is done in babies and for full-term babiesactually age two to four weeks
you can already have an accurate test. and the reason why they might get one or the doctor mightorder one is for example, if they have a geneticreason to maybe have cf, their parents carry the gene or they could have anabnormal newborn screen. now every baby who is born in the hospital gets a newborn screen. they test for metabolicfactors, things that can
potentially point to cfand if they have something abnormal there theyusually get the sweat test. so it's a test that wedo if we suspect cf. and the way it's doneis actually very simple. the baby or the person doesn'treally even have to move. so first we apply a solution to the skin, wherever the area we're testing, which encourages it to make sweat. and then we take two electrodes,one positive, one negative,
put it on the skin, turn on the current and this current stimulatesthe sweat glands. so if this is the skin, backhere is the sweat gland. so after it is stimulated tomake sweat we then collect it, send it to the lab and seehow much chloride there is. that is the sweat test. of course you can alwaysgo for genetic testing, right to the source of the gene. we already know what the geneis, and remember it's cftcr.
a thing to remember aboutthis is that even though this is the gene that causes the disease there are many variationsbetween people who have cf who have different variants of it, so it's not always as cut and dry, but for the most part analyzing this gene, seeing if it's normal can diagnose the cf. the sweat test and genetic testing are more or less answeringa yes or no question,
but to ask that questionat the appropriate time there are diagnostic cluesthat we should look for in people who might notknow that they have cf. so for people who workwith kids when they're even just babies it'simportant to watch out for people who have failure to thrive, which just means they're not gaining weight and growing as they should. and the first thing you do is make sure
the parents are feeding them correctly. but after that you start looking for what we call organic causes, or what's within the baby's metabolism that causes this, and cf is a big one. so failure to thrive, maybeit's good to do a sweat test. or people who are having a lotof frequent, long infections, especially with bacteriaor organisms that are not usually found in normal people.
for example psuedomonas, thisis something that thrives in the environment of the thick mucus that cystic fibrosis patientshave in their lungs. so this is a type ofpneumonia that's seen in a lot of cf patients, but notnecessarily in people who don't have it, so this again should tip you off to look for the cf. of course there's malnourishment,malnutrition i should say because they can eat allthe food in the world,
but if cf stops theirpancreas from helping them digest it then theywill have malnutrition. you can get things likea chest x-ray if you want to see the overinflated lungs. you can get abdominal x-ray in babies because cf can affect the intestines and sometimes it is visible on the film. but one thing, actuallyspeaking of babies, that i want to pointout is to watch out for
babies who have delayed meconium. not to gross you out,but meconium is the brown sludge that comes out of ababy when they're first born. it's kind of like their firstpoop, but it's not real poop because they haven't eatenyet, but if the sludge doesn't come out there areseveral reasons that could be and cf is one of the major reasons. so working with newbornsif they don't pass meconium within the firstfew hours like normal
babies do, it's worth itto look into that further and see if they possiblycould have cystic fibrosis. diagnosing cf is not really a huge mystery because we know the gene,we know the sweat test has a good accuracy, sothe key in cystic fibrosis diagnosis is to watch out for these clues and think of cf when you see them.