Cystic fibrosis

Definition

Cystic fibrosis is an inherited disease that causes thick, sticky mucus to build up in the lungs and digestive tract. It is the most common type of chronic lung disease in children and young adults, and may result in early death.  

Causes

Cystic fibrosis (CF) is caused by a defective gene which tells the body to produce abnormally thick and sticky fluid, called mucus. This mucus builds up in the breathing passages of the lungs and the pancreas, the organ that helps to break down and absorb food.

This collection of sticky mucus results in life-threatening lung infections and serious digestion problems. The disease may also affect the sweat glands and a man's reproductive system.

Millions of Americans carry the defective CF gene, but do not have any symptoms. That's because a person with CF must inherit two defective CF genes -- one from each parent. An estimated 1 in 29 Caucasian Americans have the CF gene. The disease is the most common, deadly, inherited disorder affecting Caucasians in the United States. It's more common among those of Northern or Central European descent.

Most children are diagnosed with CF by their 2nd birthday. A small number, however, are not diagnosed until age 18 or older. These patients usually have a milder form of the disease.

Symptoms

Because there are more than 1,000 mutations of the CF gene, symptoms differ from person to person. But in general they include:

• No bowel movements in first 24 to 48 hours of life
• Stools that are pale or clay colored, foul smelling, or that float
• Infants may have salty-tasting skin
• Recurrent respiratory infections, such as pneumonia or sinusitis
• Coughing or wheezing
• Weight loss, or failure to gain weight normally in childhood
• Diarrhea
• Delayed growth
• Fatigue

Exams and Tests

A blood test is available to help detect CF. The test looks for variations in a gene known to cause the disease. Other tests use to diagnose CF include:

• Immunoreactive trypsinogen (IRT) test. This is a standard newborn screening test for CF. A high level of IRT suggests possible CF and requires further testing.
• Sweat chloride test. This is the standard diagnostic test for CF. A high salt level in the patient's sweat indicates the disease.
• Fecal fat test
• Upper GI and small bowel series
• Measurement of pancreatic function

Cystic fibrosis may alter the results of the following tests:

• Trypsin and chymotrypsin in stool
• Secretin stimulation test
• Chest x-ray or CT scan
• Lung function tests

Treatment

An early diagnosis of CF and a comprehensive treatment plan can improve both survival and quality of life. Specialty clinics for cystic fibrosis may be helpful and can be found in many communities.

Treatment includes:

• Antibiotics for respiratory infections.
• Pancreatic enzymes to replace those that are missing.
• Vitamin supplements, especially vitamins A, D, E, and K.
• Inhaled medicines to help open the airways.
• DNAse enzyme replacement therapy to thin the mucus and makes it easier to cough up.
• Pain relievers. Research has shown that the pain reliever ibuprofen may slow lung deterioration in some children with cystic fibrosis. The results were most dramatic in children ages 5 to 13.
• Postural drainage and chest percussion.
• Lung transplant may be considered in some cases.

Support Groups

For additional information and resources, see cystic fibrosis support group.

Outlook (Prognosis)

Disease registries now show that 40% of patients with cystic fibrosis are over age 18.

Today, the average life span for those who live to adulthood is approximately 35 years, a dramatic increase over the last three decades.

Death is usually caused by lung complications.

Possible Complications

• Pneumonia, recurrent
• Pneumothorax
• Coughing up blood
• Chronic respiratory failure
• Cor pulmonale
• Liver disease
• Diabetes
• Osteoporosis and arthritis

When to Contact a Medical Professional

Call your health care provider if symptoms develop that suggest an infant or child may have cystic fibrosis.

Call your health care provider if a person with cystic fibrosis develops new symptoms, particularly severe breathing difficulty or coughing up blood.

Prevention

There is no way to prevent cystic fibrosis. Screening of family members of a cystic fibrosis patient may detect the cystic fibrosis gene in between 60 and 90% of carriers, depending on the test used.

US Food and Drug Administration. FDA Approves First DNA-based Test to Detect Cystic Fibrosis. Rockville, MD: National Press Office; May 16, 2005. Press Release P05-23.