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Cystic Fibrosis Symptoms and Diagnosis

What Are the Symptoms of Cystic Fibrosis?

Symptoms of lung disease can start in infancy, especially following upper respiratory viral infections. People with CF experience a small but progressive (worsening) loss in lung function with every passing year, leading to increased symptoms as you age. Some children remain relatively healthy throughout childhood and only start to experience a decline in their lung function when they are teenagers.

There is a wide range of severity in CF symptoms. Even within the same family, siblings can have different disease severity. Symptoms of CF can be classified into two main categories: respiratory and digestive.

The most common symptoms of CF respiratory tract disease are:

  • Chronic coughing (dry or coughing up mucus)
  • Recurring chest colds
  • Wheezing or shortness of breath
  • Frequent sinus infections
  • Very salty-tasting skin

Digestive symptoms may include greasy, foul-smelling bowel movements, severe constipation or intestinal blockage and the inability to gain weight while being constantly hungry.

How Cystic Fibrosis Is Diagnosed

  • Newborn screening. In the last decade, newborn screening has become standard and is now available in all 50 U.S. states. The newborn screen shows infants who have a high level of an enzyme called immunoreactive trypsin in their blood. This occurs when there is injury to the pancreas. The test is repeated if it is abnormal. Some states also combine this with testing for the most common gene mutation called deltaF508. The next step is to refer the infant for further testing as there are many “false-positive” tests. This entails taking a blood sample to check whether the infant has two genes that cause CF and/or performing a sweat test.
  • Genetic testing. More than 2,000 different mutations of the CF gene have been identified. Most of them are quite rare, but a few are common, like the deltaF508 mutation that is found in at least 70% of individuals with CF. Genetic testing can determine the exact mutation in most cases. For couples who want to have children, genetic testing is also important as more than 10 million Americans are carriers of a CF gene. For every pregnancy, there is a one-in-four chance that the child will have CF when both parents are carriers.
  • Sweat test. Sweat is collected from a small area on the child’s forearm, and the chloride levels are measured. Children with CF have high levels of chloride in their sweat because a lack of CFTR prevents the salt on the skin from being reabsorbed back into the sweat glands.
  • Measuring nasal lining. Another way to confirm the diagnosis is to run a small electrical current across the nasal lining (epithelium). Different solutions are applied to the nasal lining and the electrical current is measured. People with CF respond very differently than those without CF to this test, and it may help confirm a diagnosis.

When to See Your Doctor

If you or a loved one have a family history of CF and have pulmonary symptoms, have been diagnosed with CF, or experience these symptoms, consult your healthcare provider and request an evaluation at an accredited CF center. The Cystic Fibrosis Foundation website has a tool to assist in locating a care center.

Page last updated: March 4, 2020

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