Cystic Fibrosis, Part 1 — Introduction, Incidence, Symptoms and Treatment

What is cystic fibrosis?

Cystic fibrosis (CF) is an inherited disease caused by a defective gene, which affects tissues that produce mucus secretions. Affected organs typically include the lungs, the gastrointestinal tract, the pancreas and the liver. Cystic fibrosis can also affect the sweat glands and the male reproductive system.

The specific defective gene in cystic fibrosis controls production of cystic fibrosis transmembrane conductance regulator (CFTR). CFTR is a protein that controls the flow of chloride ions into and out of particular cells. In a person with CF, malfunctioning or absent CFTR prohibits chloride from entering or leaving cells, resulting in the production of thick, sticky mucus that clogs ducts or tubes in the affected organs.

The thickened mucous causes respiratory and digestive problems. A person with CF is prone to pneumonia and other lung infections, because the thickened secretions are more difficult to clear out of the breathing passages. Thick mucus in the pancreas interferes with the ability to properly digest foods. In particular, several pancreatic enzymes needed to adequately break down and absorb fats are absent. This prevents absorption of nutrients from the intestinal tract and causes malnutrition.

Incidence and Prevalence

Cystic fibrosis is an autosomal recessive genetic disorder. In order to inherit the disease, a child must have inherited the defective gene from both parents. A person can carry the defective gene, but not show symptoms of the disease. This person is known as a "carrier" of the disorder. Many people are carriers of the CF gene. In the general U.S. population, about 2 to 5 percent of people are carriers. If both parents are carriers, any child will have a 1 in 4 chance of developing the disease.

Cystic fibrosis is more common among whites of Northern Central European descent. It is much less common in other ethnic groups. Approximately 30,000 Americans have CF, and 1,000 new cases are diagnosed each year. Cystic fibrosis is usually diagnosed before age 3, but sometimes it is diagnosed later.


Checking the x-ray.

The gene responsible for CF was identified by researchers in 1989. We now realize that there are more than 200 different defective cystic fibrosis genes, causing vast variation in the severity of the disease.

In the 20 percent of cases that present in the newborn period, there might be a condition called "meconium ileus", in which passage of the first stool is delayed more than 48 hours. In an older child, the first sign of CF might be: stools that are bulky, greasy, pale, clay-colored and foul-smelling; poor weight gain; flabby muscle tone; or slow growth. Parents might notice a salty taste on the child's skin. About 50 percent of children with cystic fibrosis first see the doctor for respiratory complaints, such as pneumonia, sinusitis, frequent coughing or wheezing.

Once a diagnosis of cystic fibrosis is established, patients and parents should prepare for the following symptoms:

  • digestive problems can lead to diarrhea, weight loss, delayed growth or failure to thrive
  • excessive sodium in the seat can cause the loss of considerable water leading to dehydration
  • excessive fatigue
  • decreased fertility in males
  • decreased fertility, and complications in pregnancy and childbirth for females
  • frequent, severe infections, especially in the lungs
  • chronic infections can destroy lung tissue, a complications that ultimately takes the lives of most people with cystic fibrosis

Cystic fibrosis may result in other complications or concurrent diagnoses. Pneumothorax (collapsed lung), liver disease, diabetes, osteoporosis and osteomalacia may all result secondary to cystic fibrosis.


Caring for child in hospital.

Treatment for cystic fibrosis is aimed at improving quality of life and extending survival. This can be best accomplished by early diagnosis and treatment from a comprehensive, multidisciplinary treatment program. Specialty treatment programs for cystic fibrosis are available in many communities.

Major components of treatment include medication and postural drainage with chest percussion.

Medications include antibiotic therapy for respiratory infections and pancreatic enzymes to replace those that are missing (hence aiding digestion). Vitamin supplements can be used to correct the malabsorption.

Postural drainage with chest percussion helps break up the thick secretions in the lungs. Historically, this difficult procedure has been done by a therapist or parent manually "clapping" the child's chest and back. More recently, vests have been developed, which vibrate to aid in loosening secretions in the lungs. Inhaled bronchodilators and other breathing treatments also are used to relieve chronic obstruction of airways.

Lung transplantation has been used for some patients with cystic fibrosis. This procedure does not technically "cure" the disease, but it does allow the patient to have lungs that have not suffered from years of insult due to CF. The procedure therefore may increase survival time simply because the new lungs have not been damaged yet by the disease process.

New treatments also include replacement of the DNAse enzyme, using a medication called domase (Pulmozyme). Research in the field of genetics is exploring the possibility of correcting the disease by artificially inserting a copy of the normal gene to replace the defective cystic fibrosis gene. This treatment, called gene therapy, is currently undergoing clinical trials. Further promising research focuses on methods to correct the disorder before birth.

Possible medication side effects

The medications taken for cystic fibrosis have minimal side effects. There are no side effects from the pancreatic enzymes that are part of the treatment for CF. Some antibiotics might cause stomach cramping, nausea or diarrhea. If the CF patient is taking bronchodilators, some of those may cause nervousness or hyperactivity. At times, a child with cystic fibrosis might take steroids to reduce inflammation. Steroids can cause mood swings, ranging from anger to tearfulness.

Physical, dietary and other restrictions

The person with cystic fibrosis will have no particular dietary restrictions, unless diabetes develops from damage to the pancreas. In that case, the child will need to follow a diabetic diet and might need to take insulin. Otherwise, the child may eat any desired food and would need a diet high in calories, protein and other nutrients. High-fat diets are encouraged for children with CF. Parents, physicians and nurses are good contacts regarding the dietary needs of the child.

For more information

Part 2 — Implications for School

Part 3 — Suggested Form Letter to Communicate with Schools

National Heart, Lung, and Blood Institute

NHLBI Information Center
PO Box 30105
Bethesda, MD 20824-0105

Cystic Fibrosis Foundation


Contributed by:

Kathy Davis, MSEd, PhD
Associate Professor
Project Director, Connected Kansas Kids
Director, KU Kids Healing Place
University of Kansas Medical Center