What causes cystic fibrosis?
Cystic fibrosis is caused by a defective gene that normally helps the passage of chloride ions across cell membranes (the CFTR gene). The defective gene impairs the normal passage of salt and water into and out of cells. The inability to keep adequate water within the airways leads to thick, gooey secretions that cause airway blockage, inflammation, and infections. A similar effect is seen in the bile ducts (leading to liver disease), in the pancreas (leading to pancreatitis and malabsorption) and the intestines (causing stool blockage). The inability to absorb excess sweat leads to salt loss through the skin.
What are the major symptoms of cystic fibrosis?
- Poor growth (often this is the first sign of disease in infants)
- Chronic cough (this is the most common symptom)
- Frequent pneumonia and respiratory infection
- Fatty, soft, loose, smelly stools (from fat malabsorption)
- Nasal polyps
- Coughing up blood
- Rectal prolapse (uncommon)
- Liver disease (uncommon - jaundice and sometimes liver failure)
How is cystic fibrosis diagnosed?
Cystic fibrosis can be diagnosed based on the symptoms and the occurrence of the disease in family members. The "sweat test" is the best laboratory test for cystic fibrosis. After cleaning a small area of skin, a mild electric current is used to instill medicine into the skin to stimulate sweat production. A plastic sweat collector, gauze or paper is placed in the area with a waterproof bandage. After 30-60 minutes the sweat is analyzed for chloride content. A high value indicates an abnormality and helps confirm the diagnosis of cystic fibrosis. The test may need to be repeated to confirm the results.
Gene testing is available to look for common, known gene mutations associated with cystic fibrosis. The genetic mutation in 80 to 90% of American patients with cystic fibrosis can be identified.
What are the respiratory complications of cystic fibrosis?
Excess, thick mucousy secretions in the airways cause a chronic wet cough that produces thick yellow, white or green sputum. Inhaled bacteria and an exagerated response to viral infections cause frequent bouts of pneumonia. The persistent inflammation in the airways causes permanent lung damage that may diminish lung function. Symptoms may be intermittent or fairly constant. Eventually, shortness of breath with exertion may become severe.
How are the respiratory symptoms treated?
The goal of respiratory treatment is to enhance removal of airway secretions, reduction of inflammation, and treatment of bacterial infection.
Chest physiotherapy involves "beating" the chest with a hand or device to help loosen up secretions so they can be coughed up.
Inhaled treatments also used for asthma such as: β-agonists, glucocorticoids, and anti-inflammatory meds.
Inhaled antibiotics such as tobramycin.
Inhaled human recombinant DNase is a medicine that aids in breakdown of protein in the thickend secretions.
Often children with pneumonia or repiratory infection require oral or intravenous antibiotics and fluids.
What are the intestinal complications of cystic fibrosis?
Some infants with cystic fibrosis (15-20%) develop blockage of the intestines before passage of the first stool. This is called meconium ileus, and may require surgery to correct.
More than 85% of children with cystic fibrosis have frequent, loose, greasy, smelly stools due to malabsorption. This is due in part to inadequate enzyme production by the pancreas. This malabsorption may cause poor growth.
Despite the fact that many patients with cystic fibrosis have loose stools, constipation and intestinal blockage can occur in older children also.
How are the intestinal complications treated?
Pancreatic enzymes can be given as tablets to be taken with each meal and snack. This helps with digestion of fats and proteins. Vitamins are also given (especially the fat-soluable vitamins A, D, E and K).
Treatment for constipation may be necessary.
Surgery may be required for intestinal blockage.
What are the liver complications of cystic fibrosis?
Thick, dry, gooey bile secretions may block drainage of bile and cause liver dysfunction. Ursodiol is a medication used to help with bile flow. Rarely, liver transplantation is needed due to liver failure.
What are the pancreas complications?
Malabsorption due to decreased secretion of pancreatic enzymes.
Recurrent pancreatitis may occur in those who maintain adequate pancreatic function.
Insulin-dependent diabetes occurs in about 8% of children with cystic fibrosis after 10 years of age.
What are the sexual side effects of cystic fibrosis?
Mild delayed puberty is common in males and females. Reduced production of sperm is common in males. Pregnancy may occur in otherwise healthy females with cystic fibrosis.
What are some of the severe complications of cystic fibrosis? (see a doctor immediately)
Hemoptysis (coughing up blood) - may be due to irritated lungs and airways from coughing and infection.
Hematemesis - (vomiting blood) - may be due to liver cirrhosis that causes dilation of blood vessels and bleeding in the esophagus.
Pneumothorax - fortunately this is uncommon. Air leaks and fills the area outside of the lungs, making breathing difficult.
Allergic Aspergillosis - a fungal infection of the lungs.
Respiratory failure - this requires immediate respiratory support (example - mechanical ventilation)
Heart failure - this occurs due to chronic lung disease
What is the good news about cystic fibrosis?
Medical management for cystic fibrosis has improved greatly in recent years and children are living well into adulthood. Because cystic fibrosis is a problem generally dealing with a single protein, the promise of gene therapy and a possible cure is very exciting.
Last Updated (Monday, 22 June 2009 10:46)