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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 one of the most common chronic lung diseases in children and young adults, and may result in early death.

See also:

• Cystic fibrosis - nutritional considerations
• Neonatal cystic fibrosis screening

Causes, incidence, and risk factors

Cystic fibrosis (CF) is caused by a defective gene which causes the body to produce abnormally thick and sticky fluid, called mucus. This mucus builds up in the breathing passages of the lungs and in 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 with CF are diagnosed by age 2. 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.

Symptoms in newborns may include:

• Delayed growth
• Failure to gain weight normally during childhood
• No bowel movements in first 24 to 48 hours of life
• Salty-tasting skin

Symptoms related to bowel function may include:

• Belly pain from severe constipation
• Increased gas, bloating, or a belly that appears swollen (distended)
• Nausea and loss of appetite
• Stools that are pale or clay colored, foul smelling, have mucus, or that float
• Weight loss

Symptoms related to the lungs and sinuses may include:

• Coughing or increased mucus in the sinuses or lungs
• Fatigue
• Nasal congestion caused by nasal polyps
• Recurrent episodes of pneumonia. Symptoms in someone with cystic fibrosis include:
  • Fever
  • Increased coughing
  • Increased shortness of breath
  • Loss of appetite
  • More sputum
• Sinus pain or pressure caused by infection or polyps

Signs 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 is a standard newborn screening test for CF. A high level of IRT suggests possible CF and requires further testing.
• Sweat chloride test is the standard diagnostic test for CF. A high salt level in the patient's sweat is a sign of the disease.

Other tests that identify problems that can be related to cystic fibrosis include:

• Chest x-ray or CT scan
• Fecal fat test
• Lung function tests
• Measurement of pancreatic function
• Secretin stimulation test
• Trypsin and chymotrypsin in stool
• Upper GI and small bowel series

Treatment

An early diagnosis of CF and a comprehensive treatment plan can improve both survival and quality of life. Follow-up and monitoring are very important. If possible, patients should be cared for at cycstic fibrosis specialty clinics, which can be found in many communities. When children reach adulthood, they should transfer to a cystic fibrosis specialty center for adults.

Treatment for lung problems includes:

• Antibiotics to prevent and treat lung and sinus infections. They may be taken by mouth, or given in the veins or by breathing treatments. People with cystic fibrosis may take antibiotics only when needed, or all the time. Doses are usually higher than normal.
• Inhaled medicines to help open the airways
• DNAse enzyme replacement therapy to thin mucus and make it easier to cough up
• Flu vaccine and pneumococcal polysaccharide vaccine (PPV) yearly (ask your health care provider)
• Lung transplant is an option in some cases
• Oxygen therapy may be needed as lung disease gets worse

Treatment for bowel and nutritional problems (see: Cystic fibrosis - nutritional considerations) may include:

• A special diet high in protein and calories for older children and adults (see: Cystic fibrosis nutrional considerations)
• Pancreatic enzymes to help absorb fats and protein
• Vitamin supplements, especially vitamins A, D, E, and K
• Your doctor can suggest other treatments if you have very hard stools

Care and monitoring at home should include:

• Avoiding smoke, dust, dirt, fumes, household chemicals, fireplace smoke, and mold or mildew
• Clearing or bringing up mucus or secretions from the airways. This must be done one to fours times each day. Patients, families, and caregivers must learn about doing chest percussion and postural drainage to help keep the airways clear
• Drinking plenty of fluids. This is particularly true for infants, children, in hot weather, when there is diarrhea or loose stools, or during extra physical activity
• Exercising two or three times each week. Swimming, jogging, and cycling are good options. Avoid contact sports, scuba diving, and endurance activities such as marathons

Support Groups

For additional information and resources, see: Cystic fibrosis support group

Expectations (prognosis)

Most children with cystic fibrosis are fairly healthy until they reach adulthood. They are able to participate in most activities and should be able to attend school. Many young adults with cystic fibrosis finish college or find employment.

Lung disease eventually worsens to the point where the person is disabled. Today, the average life span for people with CF who live to adulthood is approximately 35 years, a dramatic increase over the last three decades.

Death is usually caused by lung complications.

Complications

The most common complication is chronic respiratory infection.

• Bowel problems, such as gallstones, intestinal obstruction, and rectal prolapse
• Coughing up blood
• Chronic respiratory failure
• Diabetes
• Infertility
• Liver disease or liver failure, pancreatitis, biliary cirrhosis
• Malnutrition
• Nasal polyps and sinusitis
• Osteoporosis and arthritis
• Pneumonia, recurrent
• Pneumothorax
• Right-sided heart failure (cor pulmonale)

Calling your health care provider

Call your health care provider if an infant or child has symptoms of cystic fibrosis.

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

Call your health care provider if you or your child experiences:

• Fever, increased coughing, changes in sputum or blood in sputum, loss of appetite, or other signs of pneumonia
• Increased weight loss
• More frequent bowel movements or stools that are foul-smelling or have more mucus
• Swollen belly or increased bloating

Prevention

There is no way to prevent cystic fibrosis. Screening those with a family history of the disease may detect the cystic fibrosis gene in 60 - 90% of carriers, depending on the test used.

References

Boat TF, Acton JD. Cystic fibrosis. In: Kliegman RM, Behrman RE, Jenson HB, Stanton BF, eds. Nelson Textbook of Pediatrics. 18th ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 400.

Farrell PM, Rosenstein BJ, White TB, et al. Guidelines for diagnosis of cystic fibrosis in newborns through older adults: Cystic fibrosis consensus report. Journal of Pediatrics. Aug 2008;153(2).

Stallings VA, Stark LF, Robinson KA, Feranchak AP, Quinton H. Evidence-based practice recommendations for nutrition-related management of children and adults with cystic fibrosis and pancreatic insufficiency: Results of a systematic review. Journal of the American Dietetic Association. May 2008;108(5).

Yankaskas JR, Marshall BC, Sufian B, et al. Cystic fibrosis adult care: consensus conference report. Chest. 2004;125(1 suppl):1S-39S. Review.

Mogayzel PJ Jr, Flume PA. Update in cystic fibrosis 2009. Am J Respir Crit Care Med. 2010 Mar 15;181(6):539-44.

Tuchman LK, Schwartz LA, Sawicki GS, Britto MT. Cystic fibrosis and transition to adult medical care. Pediatrics. 2010 Mar;125(3):566-73.

Borowitz D, Robinson KA, Rosenfeld M, et al. Cystic Fibrosis Foundation evidence-based guidelines for management of infants with cystic fibrosis. J Pediatr. 2009 Dec;155(6 Suppl):S73-93.