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Cystic fibrosis

Mucoviscidosis, CF

Overview

Cystic fibrosis (CF) is an inherited disease characterized by the buildup of thick, sticky mucus that can damage many of the body's organs. The disorder's most common signs and symptoms include progressive damage to the respiratory system and chronic digestive system problems. The features of the disorder and their severity varies among affected individuals.

Mucus is a slippery substance that lubricates and protects the linings of the airways, digestive system, reproductive system, and other organs and tissues. In people with cystic fibrosis, the body produces mucus that is abnormally thick and sticky. This abnormal mucus can clog the airways, leading to severe problems with breathing and bacterial infections in the lungs. These infections cause chronic coughing, wheezing, and inflammation. Over time, mucus buildup and infections result in permanent lung damage, including the formation of scar tissue (fibrosis) and cysts in the lungs.

Most people with cystic fibrosis also have digestive problems. Some affected babies have meconium ileus, a blockage of the intestine that occurs shortly after birth. Other digestive problems result from a buildup of thick, sticky mucus in the pancreas. The pancreas is an organ that produces insulin (a hormone that helps control blood sugar levels). It also makes enzymes that help digest food. In people with cystic fibrosis, mucus blocks the ducts of the pancreas, reducing the production of insulin and preventing digestive enzymes from reaching the intestines to aid digestion. Problems with digestion can lead to diarrhea, malnutrition, poor growth, and weight loss. In adolescence or adulthood, a shortage of insulin can cause a form of diabetes known as cystic fibrosis-related diabetes mellitus (CFRDM).

Symptoms - Cystic fibrosis

Cystic fibrosis signs and symptoms vary, depending on the severity of the disease. Some people may not experience symptoms until adolescence or adulthood.

People with cystic fibrosis have a higher than normal level of salt in their sweat. Parents often can taste the salt when they kiss their children. Most of the other signs and symptoms of cystic fibrosis affect the respiratory system or the digestive system. However, adults with cystic fibrosis are more likely to have atypical symptoms, such as pancreatitis, diabetes and infertility.

Respiratory signs and symptoms:

The thick and sticky mucus associated with cystic fibrosis clogs the tubes that carry air in and out of your lungs. This can cause:

  • A persistent cough that produces thick (sputum) mucus
  • Wheezing
  • Breathlessness
  • Exercise intolerance
  • Repeated lung infections
  • Inflamed nasal passages or a stuffy nose

 Digestive signs and symptoms:

The thick mucus can also block tubes that carry digestive enzymes from your pancreas to your small intestine. Without these digestive enzymes, your intestines can't fully absorb the nutrients in the food you eat. The result is often:

  • Foul-smelling, greasy stools
  • Poor weight gain and growth
  • Intestinal blockage, particularly in newborns (meconium ileus)
  • Severe constipation

Frequent straining while passing stool can cause part of the rectum — the end of the large intestine — to protrude outside the anus (rectal prolapse). When this occurs in children, it may be a sign of cystic fibrosis. Parents should consult a physician knowledgeable about cystic fibrosis. Rectal prolapse in children may require surgery.

Causes - Cystic fibrosis

Cystic fibrosis CF is caused by mutations in the Cystic Fibrosis Transmembrane Regulator gene (CFTR). More than 2000 mutations in this gene have been identified. This gene provides the instructions for the CFTR protein. In normal cells, the CFTR protein acts as a channel that allows cells to release chloride and other ions (Chloride is a component of sodium chloride, a common salt found in sweat). But in people with CF, this protein is defective and the cells do not release the chloride. The result is an improper salt balance in the cells which leads to thick, sticky mucus.

Children must inherit two defective CFTR genes — one from each parent — to have Cystic fibrosis.

Prevention - Cystic fibrosis

If you or your partner has close relatives with cystic fibrosis, you both may want to undergo genetic testing before having children. The test, which is performed in a lab on a sample of blood, can help determine your risk of having a child with cystic fibrosis.

If you're already pregnant and the genetic test shows that your baby may be at risk of cystic fibrosis, your doctor can conduct additional tests on your developing child.

Genetic testing isn't for everyone. Before you decide to be tested, you should talk to a genetic counselor about the psychological impact the test results might carry.

Diagnosis - Cystic fibrosis

Early diagnosis means treatment can begin immediately. In the screening test, a blood sample is checked for higher than normal levels of aimmunoreactive trypsinogen, or IRT, released by the pancreas.

A newborn's IRT may be high because of premature birth or a stressful delivery. For that reason other tests are needed to confirm a diagnosis of cystic fibrosis:

  • Sweat test. A sweat-producing chemical is applied to a small area of skin. The sweat test is usually done when the infant is a month old, to ensure the sample is large enough to be analyzed. The sweat test can determine if the infant carries the cystic fibrosis gene or has the condition. Testing must be done at a center specializing in cystic fibrosis.
  • Genetic testing. DNA samples from blood can be checked for specific defects on the gene responsible for cystic fibrosis. CFTR is the only gene known to be associated with cystic fibrosis.

    Additional reasons for genetic testing or screening of this gene may include:
  • Diagnosis in individuals with symptoms of CF or with congenital absence of the vas deferens (CAVD)
  • Prenatal diagnosis of a fetus at risk
  • Carrier testing for at-risk relatives and their reproductive partners or for population screening
  • Preimplantation genetic diagnosis for pregnancies at high risk for CF

Prognosis - Cystic fibrosis

Life expectancy for people with CF depends largely upon access to health care. Today, therapies exist that can increase the possibility of CF children remaining healthy until they become adults.  As lung function declines, the individual becomes disabled.  The average life span averages around 40 years of age — substantially higher than in decades past when those with cystic fibrosis did not live past grade school. Generally, lung complications are the cause of death in CF, which is why targeting therapies at the lungs is so critically important.

Treatment - Cystic fibrosis

There is no cure for cystic fibrosis, but treatment can ease symptoms and reduce complications. Close monitoring and early, aggressive intervention is recommended. Managing cystic fibrosis is complex, so consider obtaining treatment at a center that specializes in cystic fibrosis. Exercise is important to maintain lung health, especially for people with CF.

The goals of treatment include:

  • Preventing and controlling lung infections
  • Loosening and removing mucus from the lungs
  • Preventing and treating intestinal blockage
  • Providing adequate nutrition

Medications:
Many drugs are now approved to manage the disease. The options include:

  • Antibiotics to treat and prevent lung infections
  • Mucus-thinning drugs to help you cough up the mucus, which improves lung function
  • Bronchodilators to help keep your airways open by relaxing the muscles around your bronchial tubes
  • Oral pancreatic enzymes to help your digestive tract absorb nutrients

Chest physical therapy:

Loosening the thick mucus in the lungs makes it easier to cough up. Chest physical therapy helps loosen mucus. It is usually done from one to four times a day. A common technique is clapping with cupped hands on the front and back of the chest.

Mechanical devices also can help loosen lung mucus. These include a vibrating vest or a tube or mask you breathe into.

Pulmonary rehabilitation:

Your doctor may recommend a long-term program to improve your lung function and overall well-being. Pulmonary rehabilitation is usually done on an outpatient basis and may include:

  • Exercise training
  • Nutritional counseling
  • Breathing techniques
  • Psychological counseling and group support

Surgical and other procedures:

  • Nasal polyp removal. Your doctor may recommend surgery to remove nasal polyps that obstruct breathing.
  • Oxygen therapy. If your blood-oxygen level declines, your doctor may recommend you sometimes breathe pure oxygen to prevent high blood pressure in the lungs (pulmonary hypertension).
  • Endoscopy and lavage. Mucus may be suctioned from obstructed airways through an endoscope.
  • Feeding tube. Cystic fibrosis interferes with digestion, so you can't absorb nutrients from food very well. Your doctor may suggest temporarily using a feeding tube to deliver extra nutrition while you sleep. This tube may be threaded through your nose to your stomach or surgically implanted into the abdomen.
  • Bowel surgery. If a blockage develops in your bowel, you may need surgery to remove it. Intussusception, where a section of bowel has folded in on itself, also may require surgical repair.
  • Lung transplant. If you have severe breathing problems, life-threatening lung complications or increasing resistance to antibiotics used to treat lung infections, lung transplantation may be an option. Because both lungs are affected by cystic fibrosis, both need to be replaced. CF does not recur in transplanted lungs.

Resources - Cystic fibrosis

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