Understanding Cystic Fibrosis

Doctor examining patient with stethoscope
Blend Images - Jose Luis Pelaez Inc/Brand X Pictures/Getty Images

Cystic fibrosis (CF) is an inherited disease caused by a genetic defect that interferes with the body's ability to carry salt and water to and from cells. This causes a buildup of thick mucus that clogs up the lungs and digestive organs. Many people recognize cystic fibrosis as a lung disease but are unaware that the mucus buildup affects other organs as well.

Organs affected by CF include:

  • Lungs
  • Pancreas
  • Liver
  • Intestines
  • Sinuses
  • Reproductive organs

Cystic fibrosis is one of the most common genetic diseases and affects about 1 in every 2500 babies born in the United States. It is most common among Caucasians and Hispanics and rarely occurs in people of African or Asian descent.


The symptoms of CF can vary depending on the stage of the disease and the organs that are affected.

Early symptoms:

  • Increased appetite
  • Poor growth
  • Oily, bulky, foul-smelling bowel movements
  • Salty-tasting skin
  • Frequent coughs
  • Frequent respiratory infections
  • Difficulty breathing

Advanced symptoms appear in the form of complications, including:

  • Unexplained weight loss
  • Diabetes
  • Pancreatitis
  • Liver disease
  • Infertility


Cystic fibrosis is diagnosed by testing blood, sweat or fetal cells for the presence of substances or genes found in CF patients.

If an expectant couple knows or suspects that they might be carriers of the CF trait, an amniocentesis or chorionic villus sampling can be done during pregnancy to determine if the baby will have the disease.

Currently, 40 states include cystic fibrosis in their newborn screening tests. Blood is taken from the baby’s heel before he or she goes home from the hospital. The blood is sent to a state laboratory and if the defect is detected the primary care physician and local health agencies will be notified.

Infancy and Childhood
If not detected at birth, cystic fibrosis is often diagnosed in the first year or two of life when a child begins to show the typical warning signs. The traditional test for cystic fibrosis is the sweat test. Because the body is not able to use all the salt it takes in, most people with cystic fibrosis will usually excrete larger than normal amounts of salt in their sweat.

In a sweat test, electrodes are placed on the patient's skin to stimulate the sweat glands. Sweat is collected and sent to a laboratory to measure the salt content. The sweat test is not painful and has been used for many years to diagnose cystic fibrosis.


There is no cure for cystic fibrosis. Treatment involves a combination of medication, diet, exercise, and therapies designed to control symptoms and prevent complications.

Medications are prescribed to:

  • Prevent and control respiratory infections
  • Keep airway open and help with breathing
  • Loosen and remove sticky mucous
  • Help the body absorb nutrients

Diet and nutrition plans are prescribed to:

  • Replace vitamins that cannot be stored
  • Ensure calorie intake meets high energy demands
  • Ensure adequate nutrient intake for proper growth and development
  • Replace salt that is lost through sweat

    Exercise and therapies are prescribed to:

    • Strengthen the heart and lungs
    • Loosen and clear mucus
    • Improve endurance and overall physical condition
    • Increase the amount of oxygen delivered to tissues


    CF is caused by a defect in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. The job of the CFTR gene is to make a protein that controls the movement of salt and water in and out of all the cells in our bodies.

    Each of us has two copies of the CFTR gene because we got one from each of our parents. Sometimes the CFTR gene that we get from our parents is abnormal, but that doesn't always mean we will have CF.

    If a person inherits:

    • 2 normal CFTR genes: He or she will not have CF and will not be a carrier.
    • 1 normal CFTR gene and 1 abnormal CFTR gene: He or she will not have CF but will carry the defective gene and could pass it on to his or her children.
    • 2 abnormal CFTR genes: He or she will have CF disease.


    Because cystic fibrosis is an inherited disease, it cannot be prevented. However, the presence of the defective CFTR gene can be detected by a simple blood test. Before conceiving a child, couples who know or suspect that one or both partners might carry the CF defect should seek genetic counseling to determine their risk of passing on CF disease.

    Living With Cystic Fibrosis

    It wasn't so long ago that children with cystic fibrosis rarely lived beyond adolescence. Now, much is known about the disease that was not known in the past. This knowledge has led to treatment regimens that allow people with cystic fibrosis to live active and productive lives well into adulthood. People living with cystic fibrosis need to take extra precautions against infections. They will also need to take digestive enzymes, inhaled antibiotics, and other medicines for the rest of their lives. Men are usually infertile, women may be less fertile but still able to conceive.

    If Your Child Is Diagnosed

    Your family doctor or pediatrician will most likely continue to provide care with the help of a team of specialists. He or she will probably refer you to the cystic fibrosis center in your area. If not, ask for the referral. Cystic fibrosis centers are operated by physicians and health care professionals that specialize in the disease and are best equipped to monitor your child and prescribe treatment based on the most current research. At the center, your child will see a team of providers including a pulmonologist (lung specialist) and nutritionist. The cystic fibrosis center is also a good place to get information about the community and ​national resources available to you.

    Cystic Fibrosis. National Heart Lung and Blood Institute: Disease and Conditions Index. August 2007.