How common are false positives with cystic fibrosis tests?

Rare. Genetic testing has a very low false positive rate, sweat cloride i less precise.
DNA vs. sweat tests. For sweat tests, do not trust a laboratory which is not accredited by the Cystic Fibrosis Foundation. "Sweat tests should be done at a Cystic Fibrosis Foundation-accredited care center". See http://www.cff.org/AboutCF/Testing/
Uncommon. False positive sweat tests to diagnose CF are very uncommon. Genetic testing should never have false positive results. However, newborn screening for CF is frequently positive in babies who have one copy of the CF gene (cf carriers). A positive newborn screening for CF is not a diagnosis of CF unless the baby has a positive sweat test or positive genetic testing with two mutations identified.

Related Questions

How typical are false positives on cystic fibrosis tests?

Not Typical. Certain rare conditions can also lead to high sweat chloride levels (the gold standard test for cystic fibrosis). However, these rare conditions (there's a list) will cause the patient to exhibit different symptoms than those consistent with cystic fibrosis, so the sweat chloride test is considered to be reliable in diagnosing CF in conjunction with the patient's history and physical exam. Read more...
Which CF test. Depends on the type of CF test you are referring to. If it is newborn screening test (irt), then there are several conditions that can cause an elevated irt besides cf. For sweat chloride testing done by Pilocarpine iontophoresis, there are several rare conditions that can cause a false positive test. Please consult your local CF center or pediatric pulmonologist for more information. Read more...

How frequent are false positives on cystic fibrosis tests?

As high as 15% The sweat chloride test is still the gold standard diagnostic test for cystic fibrosis. The accuracy of this test is highly dependent on the method used and the lab it is performed in. I only trust a result that is performed in a center that is certified by the cystic fibrosis foundation. Some reasons for false positives include: lab error, malnutrition, & eczema. Read more...

My son had a positive sweat test for cystic fibrosis. What next?

Specialist. Around the country there are specialists for the care of these kids. Best to talk to your pediatrician and arrange to see one. Read more...
CF center. Hopefully you were referred to a cystic fibrosis center of excellence, where your son can be further evaluated and receive comprehensive care. Read more...
CFF.org. In addition to the answers provided, checking with your local children's hospital and the cff.Org for more information about your care is suggested. Read more...

Can you test positive for 2 mutations of cystic fibrosis on one copy of a gene? I am 43 and have 2 mutations and they are testing my mother.

Cystic Fibrosis. It is possible to have multiple mutations for cystic fibrosis on one copy of a gene. There are more than 1700 mutations of the cystic fibrosis gene. More about cystic fibrosis genetics via the Cystic Fibrosis Foundation: https://www.cff.org/What-is-CF/CF-Genetics/ Read more...

What are the common symptoms of having cystic fibrosis?

Cough + sputum. If above applies, kiss him/her on the skin. If you taste salt it might be cf. A simple sweat test will rule it in or out. Read more...
Vary. They vary among individuals. Failure to gain weight, diarrhea or fatty stool, cough, frequent lung and sinus infections are some of the common symptoms. Read more...

Is there a common age to start showing signs of cystic fibrosis?

Birth to teen years. The most common variant of CF is detected at birth or would appear shortly thereafter anyway. Most cases are caught by the teen years, but rarer forms show up as late as 30 or so. Read more...

Can an early cystic fibrosis test rule out the possibility of a late in life diagnosis?

Depends on test. Depending on the original test that was performed, it is unlikely that a diagnosis of CF will be made later in life. Most of the testing that is done today is highly accurate. If you are referring to yourself, at age 31, if the diagnosis of CF has not yet been made, and you have been relatively healthy all of your life, i would say it is unlikely you have it. Read more...

Can you tell me what heterozygous 57 have to do with the chances of being cystic fibrosis positive?

Cystic fibrosis. This is a start. http://www.cff.org/AboutCF/Testing/Genetics/GeneticCarrierTest/ also your ObGyn and/or a genetics specialist can help explain. . Read more...