Free
E-newsletter
Subscribe to Housecall
Our weekly general interest
e-newsletter keeps you up to date
on a wide variety of health topics.
Mayo Clinic Housecall
Stay up to date on the latest health information.
What you get
- Free weekly e-newsletter
- Mayo Clinic expertise
- Recipes, tools and other helpful information
- We do not share your e-mail address
Tests and diagnosis
By Mayo Clinic staff
Newborn screening and diagnosis
Every state in the U.S. now routinely screens newborns for cystic fibrosis. Early diagnosis means treatment can begin immediately. In the screening test, a blood sample is checked for higher than normal levels of a chemical (immunoreactive trypsinogen, or IRT) released by the pancreas.
A newborn's IRT may be high because of premature birth or a stressful delivery. For that reason other tests are needed to confirm a diagnosis of cystic fibrosis:
- Sweat test. A sweat-producing chemical is applied to a small area of skin. The collected sweat is then tested to see if it's saltier than normal.
- Genetic testing. DNA samples from blood or saliva can be checked for specific defects on the gene responsible for cystic fibrosis.
The sweat test is usually done when the infant is a month old, to ensure the sample is large enough to be analyzed. The sweat test can determine if the infant carries the cystic fibrosis gene or has the condition. Testing should be done at a center specializing in cystic fibrosis.
Testing of older children and adults
Cystic fibrosis tests may be recommended for older children and adults who weren't screened at birth. Your doctor may suggest genetic and sweat tests for cystic fibrosis if you have recurring bouts of inflamed pancreas (pancreatitis), nasal polyps, chronic sinus or lung infections, bronchiectasis, or male infertility.
Testing after diagnosis
If you have cystic fibrosis, you will need regular tests to help manage the condition:
- Imaging tests. Damage to your lungs or intestines can be monitored with X-rays, CT scans and MRI.
- Lung function tests. These tests measure the size of your lungs, how much air you can breathe in and out, how fast you can breathe in and out, and how well your lungs deliver oxygen to your blood.
- Sputum culture. Your spit (sputum) is analyzed for bacteria.
- Organ function tests. Blood tests can measure the health of your pancreas and liver. Children with cystic fibrosis should be regularly tested for diabetes after age 10.
- What is cystic fibrosis? National Heart, Lung, and Blood Institute. http://www.nhlbi.nih.gov/health/health-topics/topics/cf/. Accessed March 26, 2012.
- Goldman L, et al. Cecil Medicine. 24th ed. Philadelphia, Pa.: Saunders Elsevier; 2012. http://www.mdconsult.com/books/about.do?about=true&eid=4-u1.0-B978-1-4377-1604-7..C2009-0-42832-0--TOP&isbn=978-1-4377-1604-7&uniqId=327451096-2. Accessed March 26, 2012.
- Kliegman RM, et al. Nelson Textbook of Pediatrics. 19th ed. Philadelphia, Pa.: Saunders Elsevier; 2011. http://www.mdconsult.com/books/about.do?about=true&eid=4-u1.0-B978-1-4377-0755-7..C2009-0-60010-6--TOP&isbn=978-1-4377-0755-7&uniqId=327451096-2. Accessed March 27, 2012.
- Cystic fibrosis. National Library of Medicine. http://ghr.nlm.nih.gov/condition/cystic-fibrosis. Accessed April 2, 2012.
- What is bronchiectasis? National Heart, Lung, and Blood Institute. http://www.nhlbi.nih.gov/health/dci/Diseases/brn/brn_whatis.html. Accessed March 27, 2012.
- Cohen-Cymberknoh M, et al. Managing cystic fibrosis: strategies that increase life expectancy and improve quality of life. American Journal of Respiratory and Critical Care Medicine. 2011;183:1463.
- Rogan MP, et al. Cystic fibrosis transmembrane conductance regulator intracellular processing, trafficking, and opportunities for mutation-specific treatment. Chest. 2011;139:1480.
- Mogayzel PJ, et al. Update in cystic fibrosis 2010. American Journal of Respiratory and Critical Care Medicine. 2011;183:1620.
Find Mayo Clinic on