Cystic fibrosis

Definition
Cystic fibrosis is an inherited disease that affects sodium channels in the body and causes respiratory and digestive problems.

Causes, incidence, and risk factors

Cystic fibrosis affects the mucus and sweat glands of the body and is caused by a defective gene. Thick mucus is formed in the breathing passages of the lungs and this predisposes the person to chronic lung infections.

Many pancreatic enzymes involved in the breakdown and absorption of fats in the intestine are absent, causing malabsorption (inadequate absorption of nutrients from the intestinal tract) and malnutrition.

Most males with cystic fibrosis are infertile. About one in 2500 Caucasians is affected, and 2-5% of Caucasians carry the cystic fibrosis gene.

It is the most common fatal hereditary disorder affecting Caucasians in the United States. It is most common among Caucasians of Northern or Central European descent and is much less common in other ethnic groups. Risk factors include a family history of cystic fibrosis or unexplained infant death.

Symptoms

     
  • No meconium (bowel movements) in first 24 to 48 hours of life  
  • Stools, pale or clay colored, foul smelling, or stools that float  
  • Skin may taste salty (infants)  
  • Recurrent persistent respiratory infections, such as pneumonia or sinusitis  
  • Coughing or wheezing  
  • Weight loss  
  • Diarrhea  
  • Delayed growth  
  • Easy fatigue

Signs and tests

     
  • Sweat chloride test  
  • DNA testing  
  • Fecal fat test  
  • Upper GI and small bowel series  
  • Measurement of pancreatic function

This disease may also alter the results of the following tests:

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

Treatment

Early recognition of cystic fibrosis and a comprehensive, multidisciplinary treatment program can lengthen survival time and improve quality of life. Specialty clinics for cystic fibrosis can be found in many communities and may be helpful.

Medications include antibiotics for respiratory infections and pancreatic enzymes to replace those which are missing. Vitamin supplements are sometimes prescribed. Inhaled bronchodilators are used to relieve chronic obstruction of the airways.

A recent study showed 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. More research is being done.

Other treatments include postural drainage and chest percussion, and other breathing treatments.

Lung transplant may be considered in some cases.

New treatments include replacement of the DNAse enzyme. This is available as a medication called dornase (Pulmozyme). Genetic research is ongoing in hopes of correcting the disease by artificially inserting a “normal” gene into the person. This treatment is called gene therapy, and an intranasal form of gene therapy is currently undergoing clinical trials. Research on possible methods which could be used to correct the disorder before birth seems promising.

Support Groups
The stress of illness can often be helped by joining a support group where members share common experiences and problems. See cystic fibrosis - support group.

Expectations (prognosis)

About 40% of children with cystic fibrosis live beyond age 18. The average life span for those who live to adulthood is 30-33.

Death is usually caused by pulmonary (lung) complications.

Complications

     
  • Pneumonia, recurrent  
  • Pneumothorax  
  • Hemoptysis (coughing up blood) needs to be linked  
  • Chronic respiratory failure  
  • Cor pulmonale  
  • Liver disease  
  • Diabetes mellitus  
  • Osteoporosis and arthritis

Calling your health care provider

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
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.

Johns Hopkins patient information

Last revised: December 8, 2012
by Armen E. Martirosyan, M.D.

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