Cystic fibrosis (CF) is a hereditary disorder that causes serious damage to the lungs, digestive system, and other organs of the body. Cystic fibrosis affects the cells that produce mucus, sweat, and digestive fluids. These secretions are normally thin and slippery. But in people with CF, a defective gene causes the secretions to become thick and sticky. Instead of acting as lubricants, these secretions clog tubes, ducts, and passageways — particularly in the lungs and pancreas. Although cystic fibrosis is progressive and requires daily care, people with CF can usually attend school and work. They often experience a better quality of life than individuals with CF did in past decades. Improvements in screening and treatments mean that people with CF can now live into their mid to late 30s or 40s, and some even into their 50s.
Due to newborn screening, cystic fibrosis can often be diagnosed within the first month of life, before symptoms appear. However, individuals born before newborn screening became available may not be diagnosed until signs and symptoms of CF develop. The signs and symptoms of cystic fibrosis vary depending on the severity of the disease. Even in the same person, symptoms may get better or worse over time. Some people may not show symptoms until adolescence or adulthood. Individuals who are not diagnosed until adulthood typically have a milder form of the disease and are more likely to have atypical symptoms, such as recurrent episodes of inflammatory pancreatitis, infertility, and repeated pneumonia. People with cystic fibrosis have a higher-than-normal level of salt in their sweat. Parents may often notice this when they kiss their children and taste the salt. Most other signs and symptoms of CF affect the respiratory system and the digestive system.
The thick and sticky mucus associated with cystic fibrosis clogs the tubes that carry air into and out of your lungs. This can cause signs and symptoms such as a persistent cough that produces thick mucus (phlegm), wheezing, difficulty exercising, recurrent lung infections, inflamed nasal passages or a blocked nose, and recurrent sinusitis.
Thick mucus can also block the tubes that carry digestive enzymes from the pancreas to the small intestine. Without these digestive enzymes, your intestines are unable to fully absorb the nutrients in the food you eat. The result is often foul-smelling, greasy stools, poor weight gain and growth, intestinal blockage, especially in newborns (meconium ileus), chronic or severe constipation, which may include frequent straining during bowel movements, eventually causing part of the rectum to protrude outside the anus (rectal prolapse).
In cystic fibrosis, a defect (mutation) in a gene — the cystic fibrosis transmembrane conductance regulator (CFTR) gene — changes a protein that controls the movement of salt in and out of cells. The result is thick, sticky mucus in the respiratory, digestive, and reproductive systems, as well as increased salt in sweat. There are many different possible defects in the CFTR gene. The type of gene mutation is associated with the severity of the condition. Children must inherit one copy of the defective gene from each parent to have the disease. If they inherit only one copy, they will not develop cystic fibrosis. However, they will be carriers and could pass the gene on to their own children.
Because cystic fibrosis is a hereditary disorder, it occurs in families, making family history a major risk factor. Although CF can occur in all races, it is most common in white individuals of Northern European descent.
Complications of cystic fibrosis can affect the respiratory, digestive, and reproductive systems, as well as other organs.
Low energy levels and weight loss are also common during exacerbations.
Nutritional deficiencies. Thick mucus can block the ducts that carry digestive enzymes from the pancreas to the intestines. Without these enzymes, your body cannot absorb proteins, fats, or fat-soluble vitamins, which means you do not get enough nutrients. This can lead to delayed growth, weight loss, or inflammation of the pancreas (pancreatitis).
Diabetes. The pancreas produces insulin, which your body needs to use sugar properly. Cystic fibrosis increases the risk of diabetes. About 20% of teenagers and 40% to 50% of adults with CF develop diabetes.
Liver disease. The duct that carries bile from the liver and gallbladder to the small intestine can become blocked and inflamed. This may lead to liver problems such as jaundice, fatty liver disease, cirrhosis, and sometimes gallstones.
Intestinal obstruction. Intestinal blockage can occur in people with cystic fibrosis at any age. Intussusception — a condition in which one part of the intestine slides into an adjacent part like a telescoping tube — may also occur.
Distal intestinal obstruction syndrome (DIOS). DIOS is a partial or complete obstruction where the small intestine meets the large intestine. It requires urgent treatment.
Nearly all men with cystic fibrosis are infertile because the tube that connects the testes and the prostate gland (the vas deferens) is either blocked by mucus or completely absent. Certain fertility treatments and surgical
Although women with cystic fibrosis may be less fertile than women without CF, they can still conceive and have a successful pregnancy. However, pregnancy may worsen CF symptoms, so it is important to discuss potential risks with a doctor.
People with cystic fibrosis have a higher risk of developing bone thinning. They may also experience joint pain, arthritis, and muscle pain.
Because people with CF have saltier sweat, the balance of minerals in their blood can become disrupted. This makes them more prone to dehydration, especially during exercise or hot weather. Signs and symptoms include increased heart rate, fatigue, weakness, and low blood pressure.
Living with a chronic, incurable illness can lead to feelings of fear, depression, and anxiety.
If you or your partner has close relatives with cystic fibrosis, both of you may choose to undergo genetic testing before having children. The test, which is performed in a laboratory using a blood sample, can help determine your risk of having a child with CF. If you are already pregnant and the genetic test shows that your baby may be at risk for cystic fibrosis, your doctor may perform additional testing on the developing child. Genetic testing is not for everyone. Before deciding to be tested, you should speak with a genetic counselor about the potential psychological impact of the test results.
To diagnose cystic fibrosis, doctors typically perform a physical examination, review your symptoms, and conduct various tests.
Newborns are now routinely screened for cystic fibrosis. Early diagnosis means that treatment can begin right away. In a screening test, a blood sample is checked for higher-than-normal levels of a chemical called immunoreactive trypsinogen (IRT), which is released by the pancreas. A newborn’s IRT levels may be high because of a premature birth or a stressful delivery. For this reason, additional tests may be needed to confirm the diagnosis of cystic fibrosis. To determine whether an infant has cystic fibrosis, doctors may also perform a sweat test once the baby is at least 2 weeks old. A sweat-producing chemical is applied to a small area of the skin. Sweat is then collected and tested to see if it is saltier than normal. Testing performed at a Cystic Fibrosis Foundation–accredited care center helps ensure reliable results. Doctors may also recommend genetic testing to look for specific defects in the gene responsible for cystic fibrosis. Genetic testing can be used in addition to measuring IRT levels to confirm the diagnosis.
Cystic fibrosis testing may be recommended for older children and adults who were not screened at birth. Your doctor may suggest genetic testing and sweat testing for CF if you have recurrent episodes of inflammatory pancreatitis, nasal polyps, chronic sinus or lung infections, bronchiectasis, or male infertility.