What Is Cystic Fibrosis?

Understand the Causes, Symptoms, and Advances in Treatment

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Cystic fibrosis (CF) is an inherited, life-threatening disorder that damages the lungs and digestive tract. It is caused by a defective gene that triggers the production of thickened mucus which clogs airways and blocks the secretion of digestive enzymes.

Symptoms are progressive and often severe, and they may include breathing problems, recurrent lung infections, poor growth, male infertility, and the chronic inflammation of the pancreas, liver, kidneys, and heart.

CF can be diagnosed with blood tests, genetic screening, and a procedure known as a sweat chloride test.

While there is no cure for CF, there are treatments that can improve both the length and quality of one's life.

These include airway clearance techniques, inhaled antibiotics, mucus thinners, pancreatic enzymes, a high-calorie diet, and newer generation medications known as CFTR modulators. In severe cases, a lung transplant may be needed.

Understanding Cystic Fibrosis
Verywell / Emily Roberts

Cystic Fibrosis Symptoms

As a genetic disorder, cystic fibrosis is something you are born with. It may or may not present with symptoms at the time of birth and can often take months or even years before any signs of illness appear. By that time, the lungs and digestive tract may already have experienced damage that cannot be undone.

The most common early signs and symptoms of CF include:

  • Blockage of the baby's first stool (meconium)
  • Salty-tasting skin
  • A chronic cough, wheezing or colored sputum
  • Loose, greasy, and typically foul-smelling stools
  • Lung infection, often recurrent
  • Poor growth and failure to thrive

Unless these symptoms can be controlled, the stress on the lungs (and the inability to gain weight) can have a cumulative effect, affecting multiple organs and increasing the risk of disease complication.

Some of the more characteristic complications include:

Because CF causes progressive injury to cells and tissues, any damage caused to the lungs and other organs will be largely irreversible. Death will most often be the result of respiratory failure, followed by heart failure and liver failure.


Cystic fibrosis is caused by the mutation of the cystic fibrosis transmembrane receptor (CFTR) gene, which is responsible for producing the CFTR protein. This is the protein that the body needs to regulate the flow of salt and water in and out of cells. If the protein is deformed or defective, it can cause dehydration on the surface of a cell, leading to the thickening of the surrounding mucus.

CF is an autosomal recessive disorder, meaning that you need to inherit the CFTR mutation from both your mother and father to have the disease. If you only inherit one defective gene, you won't have CF but will instead be a carrier of the mutated gene.

You can inherit the disease if each of your parents either has a CFTR mutation or CF itself. If both parents are carriers, you would have a:

  • 25 percent chance of having CF
  • 50 percent chance of being a carrier
  • 25 percent chance of being unaffected

On the other hand, if one of your parents is a carrier and the other has CF, you stand a 50/50 chance of either having CF or being a carrier.

Cystic fibrosis is one of the more common genetic diseases, affecting roughly one in every 2,500 babies born in the United States.

It is most common among Caucasian and Hispanics, and occurs less frequently in people of African or Asian descent.


There are a few tests used to diagnose cystic fibrosis. They work either by directly detecting the CFTR mutation or indirectly measuring biological changes consistent with the disease. The method of diagnosis can vary during pregnancy, when the baby is born, or anytime afterward.

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Of the two standard tests commonly used to diagnose CF:

  • Sweat chloride testing, also known simply as the sweat test, measures the amount of chloride on the skin. Because CF interferes with the transfer of salt to and from cells, there will be an accumulation of salt in sweat.
  • Genetic CFTR testing is used to detect the most common mutations of the CFTR mutation. While there are over 2,000 CFTR mutations known to cause cystic fibrosis, the 23 included in the standard panel represent the most likely suspects.

During pregnancy, the CFTR genetic test can be used to test fluids obtained through an ​amniocentesis or cells extracted via chorionic villus sampling (CVS).

Newborn screening is also standardly used to diagnose CF and is today mandated in all 50 states and the District of Columbia. What this entails will differ depending on where in the United States you live. If the newborn screening results are positive, a sweat test would be used to confirm the diagnosis.


While there is no cure for cystic fibrosis, advances in treatment have extended the lifespans of those living with the disease.

The aim of CF treatment is four-fold: to prevent infections, retain lung function, normalize digestion, and slow the progression of the disease.

Among the therapeutic tools used to manage CF:

  • Airway clearance techniques (ACTs) are performed to dislodge and expel accumulated mucus from the lungs. Techniques include huff coughing, chest percussion, or chest wall oscillation.
  • A high-fat, high-calorie diet is used to compensate for the malabsorption of fats, proteins, and nutrients in the intestines.
  • Pancreatic enzyme supplements are used to bolster the digestive enzymes that the pancreas cannot produce due to the excessive build-up of mucus.
  • Antibiotics are taken daily to prevent bacterial lung infections.
  • Mucolytics—drugs used to thin mucus prior to ACTs—may be used.
  • CFTR modulators are a new class of drug that can correct certain defects in the CFTR protein and restore their regulatory function.
  • Oxygen therapy may be used during acute episodes when your breathing has been severely impaired.
  • Enteral nutrition, also known as tube feeding, may be used if you cannot sustain weight through normal nutrition.
  • Lung transplantation is considered when your lungs can no longer support survival without mechanical ventilation.


In 1938, when cystic fibrosis was first classified as a disease, children rarely lived beyond their first year of life. By the 1980s, one could expect to live as long as 20 to 25 years. Today, the picture has changed entirely with people living well into their 40s and even 50s if treatment is started early and adhered to.

This is not to suggest that CF is any less serious than it has ever been. It is a life-changing event, requiring diligence and consistency to not only cope with the disease but live the highest standard of life possible.

To this end, you need to normalize CF in your life by establishing the routines and practices to avoid the ups and downs that can cause stress and increase disability. Among the considerations, you would need to:

  • Manage your nutrition. People with CF often need twice the daily calories that other people do.
  • Exercise regularly. Fitness routines should ideally involve a minimum of 20 to 30 minutes of aerobic activity three times per week. Find something enjoyable you can do for a lifetime.
  • Keep well-hydrated. Doing so keeps the lungs and intestines working properly. Depending on your age, you should drink no less than six to eight tall glasses of water per day.
  • Perform airway clearance correctly. As your health needs change, so, too, may the types of clearance tools you need. Speak with your pulmonologist or physical therapist if you are not achieving the results you should.
  • Seek support. In addition to friends and family, you can contact the nearest chapter of the Cystic Fibrosis Foundation (CFF) to plug into a support network in your area.
  • Seek financial help. The CFF offers services that help families better cope with the high cost of CF treatment.

A Word From Verywell

While newborn screenings have dramatically increased the rate of the CF diagnoses in babies, over 25 percent of diagnoses are only made during the childhood, teen, and early adult years.

This is problematic because early diagnosis and treatment can stave many of the more severe complications of CF before any serious damage can be done. While treatment cannot stop or reverse the disease, it can ensure many more disease-free years.

To this end, it is important to know the early symptoms of CF and to speak with your doctor if you suspect your child may have the disease. This is especially true in states that screen with IRT blood tests only, which could result in as many 5 percent of children experiencing either a delayed diagnosis or a false-negative result, according to research from the University of Wisconsin School of Medicine and Public Health.

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  2. U.S. National Library of Medicine. MedlinePlus. Cystic fibrosis

  3.  Cystic Fbrosis Foundation. Types of CFTR Mutations

  4. Cystic Fibrosis Foundation. CF Genetics: The Basics

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  9. Rock MJ, Levy H, Zaleski C, Farrell PM. Factors accounting for a missed diagnosis of cystic fibrosis after newborn screening. Pediatr Pulmonol. 2011;46(12):1166-74. doi:10.1002/ppul.21509

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