Cystic fibrosis affects organs throughout the body.

Effects of CF


The upper respiratory tract—nose, nasal passages or sinuses, and the pharynx—filters and warms the air. Several abnormalities, such as nasal polyps and excess tissue growth in the nasal cavity, may affect people with CF. Chronic or recurrent sinusitis occurs when secretions become infected and cause inflammation. As in the lungs, mucus in the sinuses is abnormally thick and cannot be cleared easily; promoting accumulation of bacteria and inflammation that stimulates more mucus production. Often, the sinuses are infected with bacteria similar to those found in the lungs. Recurrent or chronic sinusitis is typically treated with antibiotics and saline irrigation. In some cases endoscopic surgery is preformed to remove polyps and promote mucus drainage.

Sinus CT scan

A CT scan of a child with CF shows that the right maxillary sinus is completely filled with mucus.

Normal sinuses compared to sinuses with CF

Compare the normal sinuses to sinuses with CF


The structure of the lung allows rapid uptake of oxygen from the air and diffusion into the bloodstream. Air is warmed and moistened in the mouth and nose, which makes it less irritating to the airways, while nose hairs trap particles such as dust, pollen, and bacteria. The filtered air then moves through branching airways that are lined with mucus to collect any particles that get through. The air travels through smaller and smaller airway branches until reaching tiny air sacs called alveoli, where oxygen and carbon dioxide are exchanged.

In CF, faulty transport of electrolytes across airway tissues leads to abnormal mucus production along the respiratory tract. This mucus is easily dehydrated and difficult to clear. Eventually, the mucus obstructs the airway, impairing the alveoli, and prevents foreign particles from being cleared, resulting in chronic lung infections.

Chronic Lung Disease

Cystic fibrosis airways are obstructed by thick mucus that make it difficult to clear infection-causing bacteria like Pseudomonas aeruginosa, Staphylococcus aureus, Hemophilus influenzae and Burkholderia cepacia. Over time, chronic bacterial infections lead to inflammation and damage to the airway walls and bronchiectasis, an abnormal stretching of the respiratory passages.

Several tests determine the extent of infection, inflammation, bronchiectasis and mucus plugging in the lungs. Spirometry (pulmonary function testing or PFT) measures the respiratory cycle as an individual breathes in and out of a mouthpiece. Changes in the rate of airflow will detect the progression of lung disease and response to therapy. More extensive pulmonary imaging procedures such as chest X-rays and chest CT scans are also used to determine the extent of CF lung disease.

Pulmonary Exacerbation

Cystic fibrosis is characterized by recurrent pulmonary problems like shortness of breath, increased cough and sputum production, fatigue and occasionally hemoptysis, or coughing up of blood. Exacerbations are caused by bacterial or viral infections in the bronchi and bronchioles leading to inflammation. Some pulmonary exacerbations can be treated at home with antibiotics, aggressive airway clearance and breathing treatments. If symptoms persist or worsen, hospitalization will likely be necessary for intravenous antibiotics and other interventions


Hemoptysis, or coughing up blood, is a common CF complication. The condition varies from streaks of blood in mucus to mouthfuls of blood that are coughed up from hemorrhage in the airway. Infection and inflammation change the pulmonary blood vessels, making them tortuous and fragile. Additionally, abnormal connections form between bronchial and pulmonary arteries that bleed easily. Infections increase the risk of hemoptysis. Minor hemoptysis is common, occurring in up to 75 percent of adults with CF. Major hemoptysis, defined as more than 200 milliliters of blood (about the volume of a can of soda), occurs much less frequently, but requires immediate attention. Medications, such as aspirin, that affect the ability of the blood to clot should be avoided


Pneumothorax, a potential life-threatening complication of CF, literally means air in the chest, but refers specifically to air surrounding the lungs. Normally, this space contains a small amount of fluid. When air is in this space because of rupture of alveoli or trauma, the surrounding lung tissue may collapse. Pneumothorax occurs in approximately 4% percent of people with CF each year and 50 percent of these individuals will have more than one occurrence. Symptoms include sudden chest pain and shortness of breath. Smaller pneumothoraces may not cause symptoms and tend to resolve themselves. Diagnosis is usually confirmed by a chest X-ray. A small pneumothorax may be managed with supplemental oxygen and monitoring, but a larger pneumothorax is treated with a chest tube to remove the air.



The pancreas, located behind the stomach in the center of the abdomen, extends into the left side of the abdomen. The pancreas is connected to the first part of the intestine, the duodenum. The pancreas secretes enzymes that aid food digestion and help to regulate blood sugar.

Abnormal Function in CF

In CF, the altered transport of electrolytes across pancreatic tissues leads to abnormal production of digestive enzymes. Decreased production of sodium bicarbonate makes pancreatic secretions dehydrated and thickened, blocking the pancreatic ducts. Despite these blockages, the pancreas continues to make more enzymes required for food digestion. The abundant enzymes damage the pancreatic tissue, eventually leading to fibrosis of the pancreas until it is no longer able to produce enough enzymes to properly digest food. The lack of bicarbonate secretion also prevents stomach acid from being neutralized when it enters the small intestine.

Pancreatic Insufficiency

Pancreatic insufficiency occurs when the pancreas loses about 90 percent of its ability to secrete digestive enzymes. People with pancreatic insufficiency are unable to digest food properly, which leads to the malabsorption of nutrients, or even malnutrition. Fat-soluble vitamins, such as A, D, E, and K, and fats, are the most important nutrients that are not absorbed. The impaired absorption of fats causes diarrhea, weight loss, and malnutrition, but supplemental pancreatic enzymes can help with digestion. Approximately 80 percent of people with CF develop pancreatic insufficiency.

Start the Normal Pancreatic Function animation by clicking on the “Play” button above or select one of the other topics to play: Pancreatic Insufficiency, Pancreatitis or Diabetes.


Pancreatic duct blockages can lead to pancreatitis, an inflammatory process that can cause severe abdominal pain, vomiting, and diarrhea. People with CF who have some pancreatic function can develop pancreatitis. However, pancreatitis is uncommon, occurring in less than 10 percent of people with CF.

Gastrointestinal Tract

Steps in digestion

How digestion occurs in the stomach or in the duodenum.

For people with cystic fibrosis, gastrointestinal (GI) complications may involve the pancreas, small intestine, liver, and large intestine. The main function of the GI tract is to digest food and remove waste products. There are many organs involved:

Mouth Glands secrete digestive enzymes that begin digestion.
Esophagus Transports food from the mouth to the stomach.
Stomach Secretes digestive enzymes and mechanically compresses the food.
Pancreas Secretes enzymes for digestion and hormones regulating metabolism.
Liver Filters the blood, removing toxins.
Gallbladder Releases bile that aids in digestion.
Small Intestine Absorbs most of the nutrients from the digestion of food.
Large Intestine Reabsorbs water and forms feces.


Large Intestine

The large intestine is involved in the reabsorption of water from the gastrointestinal tract and is also the site of feces formation and excretion. The large intestine spans the perimeter of the abdomen. The large intestine does not function normally in CF. Incompletely digested proteins, sugars, and fats, decreased electrolytes and water content make the feces very thick.

Distal Intestinal Obstruction Syndrome

Individuals with CF are prone to intestinal impaction and obstruction. Symptoms include decreased stool output, abdominal pain and distention, nausea, and vomiting. Previously known as meconium ileus equivalent, the newer terminology is distal intestinal obstruction syndrome, or DIOS. About 10 to 20 percent of people with CF will have DIOS at least once, and up to approximately 5 percent of people will have recurrences. Prompt recognition is essential for proper treatment. Physical examination and X-rays of the abdomen can diagnose this blockage. Treatment varies based upon the severity of the symptoms and degree of intestinal obstruction. Laxatives and enemas are typical therapies.

Recal Prolapse

In this condition, the lower part of the colon, called the rectum, falls out of its usual position and can be seen outside the body. Rectal prolapse can be a presenting symptom for some children with CF.

Colon Cancer

Compared with the general population, individuals with CF have a similar overall risk of cancer. But when it comes to colon cancer and other intestinal cancers, studies show, people with CF have an increased risk. The CF Foundation recommends routine colon cancer screening for adults with CFTR. The best screening test is a colonoscopy.

Small Intestine

The small intestine—comprised of the duodenum, jejunum and ileum—is the primary organ involved in absorption of nutrients. The innermost layer of the small intestine also has small, finger-like projections called villi, which are designed to absorb nutrients. Usually, stomach acid is neutralized in the duodenum and the food is mixed with pancreatic enzyme and bile from the liver. Most people with CF do not produce pancreatic enzymes or secrete enough bicarbonate to neutralize the stomach acid. The acidic contents lessen the effectiveness of pancreatic replacement therapy and can erode of the lining of the small intestine and lead to damage. The absorption of nutrients is also compromised by abnormal mucus in the intestine and overgrown of bacteria. The absorption of fat is further diminished by the inability of the ileum to absorb bile salts that aid in the digestion of fats. The absorption of fat-soluble vitamins A, D, E, and K is also diminished, leading to vitamin deficiency.

Normal digestion and digestion with CF

Compare normal digestion to digestion with CF.
(A) After food is broken down by enzymes, nutrients are normally absorbed from the intestine,
(B) into the blood stream.
(C) With CF the absorption is impaired by the presence of thick secretions.


Intussusception, the telescoping of one portion of the intestine into another, occurs rarely in people with CF. But it can lead to intestinal obstruction when fecal matter attaches to the intestinal wall and forces the intestine to fold incorrectly, leading to decreased blood flow. Eventually, part of the intestinal wall can rupture, releasing fecal matter into the abdomen. A potentially life-threatening infection in the blood stream can follow. Symptoms include severe abdominal pain, fever, low blood pressure, and bloody stools. Occurring most commonly in children with and without CF, the condition affects about one percent of adults with CF. Adequate hydration and stool softeners are necessary for prevention.


Individuals with pancreatic insufficiency often develop CF-related diabetes (CFRD) because pancreatic duct blockages and digestive enzyme damage lead to chronic inflammation and fibrosis or scarring of the pancreas. This scarring impairs the endocrine functions of the pancreas, such as regulating insulin secretion. Impaired production of insulin results in diabetes mellitus. Diabetes or impaired glucose regulation occurs in over 40 percent of people with CF over the age of 35. Cystic fibrosis-related diabetes (CFRD) has features of both Type I and Type II diabetes. Once diagnosed, strict blood glucose control is required using frequent monitoring and insulin injections. A decline in pulmonary function may be related to uncontrolled diabetes. Other complications, including: kidney, neurological and eye disease can also occur.

Neurologic Disease

Cystic fibrosis-related diabetes can damage the peripheral nervous system that controls sensation. Similar to the damage caused in the eyes, blood supply to nerves that control sensation in the hands and feet is impaired, resulting in numbness in about 20 percent of people with CFDR. Strict blood sugar control is the best prevention.

Kidney Disease

A type of kidney damage called diabetic nephropathy occurs in about 10 percent of people with CFRD. Poorly controlled CFRD can lead to kidney failure. Prevention requires strict blood sugar control and monitoring of kidney function by blood and urine tests. Medications and lifestyle modifications can also slow disease progression.

Eye Disease

Cystic fibrosis-related diabetes can damage the retina, resulting in diabetic retinopathy. Progressive damage to the small blood vessels that supply the retina, which can lead to diminished vision, occurs in up to 15 percent of people with CFRD. Untreated, vascular damage can cause scarring, bleeding, and detachment of the retina, resulting in vision loss. Strict blood glucose control is essential. An annual evaluation by an ophthalmologist is recommended.


Normal bile flow and bile flow with CF

Compare the normal bile flow to the bile flow with CF. Normal: Bile flow of the liver into the small intestine aids digestion. With CF: Thick bile in CF patients blocks the bile ducts in the liver.


Severe CF liver disease

Severe CF liver disease can lead to cirrhosis or scarring in the liver. The liver enlarges and there is increased blood pressure in the liver that causes the spleen to enlarge as well

Normal Function

The liver is a large organ located on the right side of the abdomen, just below the diaphragm. It filters blood, removing toxins and other harmful by-products of metabolism. The liver also produces bile, a fluid that is essential for the digestion of fats and for the neutralization of acidic contents of digestion. The gallbladder is a small, pouch-like structure on the underside of the liver. This organ concentrates the bile that is made by the liver and releases it in response to hormones released by the small intestine.

Abnormal Function

Cystic fibrosis affects the liver and gallbladder, resulting in abnormal bile production. The bile is dehydrated and more acidic than normal bile, reducing its flow into the small intestine. Dehydrated bile can concentrate in the gallbladder, producing gallstones, and causing cholecystitis. This inflammation of the gallbladder marked by pain, fevers, nausea, and vomiting, may require surgical removal of the gallbladder. Occasionally, gallstones can obstruct the ducts of the pancreas and cause pancreatitis.

Cirrhosis and Portal Hypertension

Obstructed bile ducts in the liver can also lead to liver damage. Focal biliary cirrhosis is caused by plugging of liver bile ducts by dehydrated bile. This obstruction leads to inflammation and eventually fibrosis of the ducts, further impairing the release of bile and overall liver function. Approximately 5% of adults with CF suffer cirrhosis of the liver, a serious complication caused by the formation of dense scarring and resulting in the destruction of liver cells.

Repeated scarring and fibrosis of the ducts affects liver blood flow, a condition known as portal hypertension. The increased blood pressure causes blood to be redirected to other blood vessels. Consequently, these vessels become enlarges and prone to life-threatening bleeding. The spleen also becomes enlarged and can be painful. As portal hypertension worsens, blood supply to the liver is compromised, leading to liver failure. Then, toxic substances normally removed by the liver remain in the bloodstream, causing confusion, coma, and eventually death. Liver transplantation is a option for people with end-stage liver disease.

Physical examination of the liver and spleen should be performed at each clinic visit. Yearly liver function tests should be obtained. Ultrasound can identify mechanical obstruction of the liver ducts or gallbladder, changes of the liver suggesting cirrhosis, and fatty changes suggesting steatosis. Therapy for liver disease should include nutritional support, preventive interventions, and management of complications.


Male Reproductive System

Cystic fibrosis affects the male reproductive system leading to bilateral absence of the vas deferens in most people. Recent medical advances have made this a potentially treatable problem. In vitro fertilization (IVF) can be used with a technique called intracytoplasmic sperm injection (ICSI). Microepididymal Sperm Aspiration (MESA) is a procedure performed for men who have bilateral absence of the vas deferens. This procedure is either done as a scheduled procedure or is coordinated with their female partner’s egg retrieval. MESA is performed in the operating room with general anesthesia utilizing the operating microscope. People usually cryopreserve sperm during this procedure for future IVF/ICSI. MESA allows for an extensive collection of sperm as compared to aspiration techniques, and is the preferred method of retrieval for men with bilateral absence of the vas deferens.

In males with CF with chronic lung disease and malnutrition, puberty is often delayed because of impaired production of sexual development hormones, follicle-stimulating hormone (FSH) and luteinizing hormones (LH). Despite this delayed onset, over 90 percent of individuals CF with adequate nutrition achieve normal height. For males with CF, there is a four-fold increase in the incidence of fluid accumulation around the testes, known as hydrocele. There is a fifteen-fold increase in the risk of having an undescended testicle.

Female Reproductive System

Women with CF can have functional reproductive abnormalities, such as absence of menstruation, related to malnutrition and chronic disease. Although there are no structural reproductive abnormalities, the quality and quantity of the cervical mucus essential to implantation of the fertilized egg can be altered. However, a woman’s overall heath will determine her fertility. With good nutrition and lung function, fertility rates approach that of the general population. However, even women with severe disease can become pregnant.

Normal flow of sperm and flow with CF

Compare the normal flow of sperm to the flow with CF.


Normal muscles and muscles with CF

Compare the normal muscles to muscles with CF.
Normal:The muscles in the pelvic floor prevent urine from escaping.
With CF: Weakened muscles in the pelvic floor can allow urine to leak during coughing.

Stress Incontinence

Almost 65 percent of women with CF will develop urine leakage, or urinary/stress incontinence, related to coughing, sneezing, laughing, and lifting. Stress incontinence occurs when the pressure inside the bladder exceeds that of the muscle that controls the release of urine. Women with worse pulmonary function are particularly at high risk for this due to chronic stress on the bladder muscles from coughing. Pelvic muscle exercises may reduce the symptoms of stress incontinence. Although more common in women, this problem can occur in males as well.

Kidney Stones

Approximately 6% of adults with CF will develop kidney stones, and about 40 percent will have a recurrence. Calcium oxalate stones are the most common stones found in people with CF. People with chronic diarrhea have altered absorption of oxalate, which may lead to the formation of calcium-based kidney stones. An increased amount of uric acid and decreased amount of citrate in the urine of people with CF also increases stone formation. People who produce small volumes of urine are at a higher risk of developing kidney stones. Kidney stones can lead to flank pain, fevers, nausea, and vomiting. If left untreated, kidney stones can cause obstruction and significant infections. Drinking large amounts of fluid and adequate pain control are the cornerstones of therapy.



Muscle weakness, particularly in the arms, legs and diaphragm, is common in individuals with CF. Malnutrition contributes greatly to muscle dysfunction. Chronic illness leads to reduction in muscle mass and strength, and impaired regulation of electrolytes, the hallmark of CF, also contributes to muscle weakness. Medications used to treat CF complications, like steroids, may worsen underlying muscle weakness. Proper nutrition and regular exercise help maintain conditioning and retain muscle mass.


Adults with CF are at a high risk for reduced bone density, known as osteoporosis. Over 70 percent of adults with CF will develop the condition. Thinning of the bones makes them more prone to fractures that may occur even without trauma. Low levels of vitamin D—due to malabsorption—impair bone formation. Individuals with CF are further prone to low vitamin D levels because they may not receive adequate sunlight exposure required for converting vitamin D into its active form. Recommendations for vitamin D supplementation are available.

This accelerated bone breakdown increases with inactivity, chronic lung disease, and steroid use. Also, inflammation from chronic lung disease may increase bone breakdown. Lung transplant recipients using immunosuppressive drugs like corticosteroids also have an accelerated rate of bone loss. Low levels of sex hormones important to bone development and delayed onset of puberty limit the time for adult bone formation, more often in men. Cystic fibrosis-related diabetes, alcohol use and cigarette smoking may also hasten the onset of osteoporosis.

Adults with CF should be screened every 1-5 years with a DEXA (Dual-energy radiograph absorptiometry) scan. Using two separate X-rays, it measures bone density at the spine, femur, and other sites. Patients should also have serum vitamin D levels checked annually along with diabetes screening. Prevention of osteoporosis involves implementation of a health plan that emphasizes diet and weight-bearing exercise.

The effects of CF on bone density

The effects of CF on bone density
Normal: Normal bone is composed of a meshwork of collagen and calcium.
With CF: The bones of patients with CF are less dense leading to osteoporosis.