Getting the Diagnosis

Now that cystic fibrosis has become much more understood in the medical world, the importance of testing for this disease at a very young age has also been recognized. All states in the US, therefore, screen all newborns for CF. Typically, this is done with a genetic test and/or a blood test. The genetic test is able to determine if the newborn's CFTR genes are working properly and the blood test is able to check the function of the pancreas.

If either one of these tests suggest that the newborn may have cystic fibrosis, your healthcare provider will then want to confirm this by using a sweat test. This is one of the most accurate ways to get a confirmation of a cystic fibrosis diagnosis. The provider will try and get the newborn to sweat in a small patch on either their arm or leg by rubbing a sweat-producing chemical on an area of skin. Once the newborn has begun sweating, they will apply an electrode which will cause a mild electrical current to run through the skin, which helps get the medication into the skin and initiate sweating. The provider will then collect and analyze a small sample of the sweat. Specifically, they will be measuring the amount of salt in the sweat. If high levels of salt are observed, this can confirm the diagnosis for cystic fibrosis.

At this point, the provider may want to order a series of other tests. There may be more genetic tests to determine the exact type of CFTR gene mutation, which can help the patient and caregivers understand what the progression of their type of CF may look like. A chest X-ray can also be beneficial to look at the inflammation level in the lungs (since this is the most common problem with CF). A sinus X-ray may also be ordered to check the level of sinus infections, another common CF complication. Lung function tests can help your provider see how well the lungs are providing oxygen to the blood. Finally, a sputum culture (where the provider will take a sample of spit/mucus) will help determine whether or not there is bacteria present in the lungs (especially Pseudomonas aeruginosa). If this bacteria is present, it indicates that the cystic fibrosis has advanced and that a more aggressive treatment will be needed.

Cystic fibrosis can also be detected during pregnancy through prenatal testing. This will include amniocentesis and chorionic villus sampling. In amniocentesis, a small hollow tube will be inserted into the uterus through the abdomen. They will then take a sample of some of the amniotic fluid surrounding the baby to test for CFTR gene mutations. With chorionic villus sampling, a small tube is inserted up through the vagina and past the cervix into the placenta. A small piece of placenta will be taken and tested for CFTR gene mutations.

Finally, if you are worried that you may be a carrier for cystic fibrosis, you can be tested by a genetics counselor. They will take either a blood or saliva sample and can determine if you carry the malfunctioning CFTR gene.

References:
How Is Cystic Fibrosis Diagnosed? (2013, December 26). Retrieved January 31, 2015, from http://www.nhlbi.nih.gov/health/health-topics/topics/cf/diagnosis

Cystic fibrosis. (2012, June 13). Retrieved January 31, 2015, from http://www.mayoclinic.org/diseases-conditions/cystic-fibrosis/basics/tests-diagnosis/con-20013731