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CF Source

CF Progression

Explore below to see how the progression of CF affects different parts of the body over time.


People with cystic fibrosis (CF) experience a loss of lung function over time. The time when these lung problems appear can vary among people with CF. For most, the effect on the lungs is the most serious, life-threatening complication caused by CF.

Lung damage is seen across people of all ages with CF, including infants. This is primarily the result of mucus buildup, infections, and inflammation.

These factors may result in progressive damage to the lungs’ airways:
  • This damage may occur before a loss of lung function is even detected by a spirometer. A spirometer is an instrument that measures lung function, or FEV1 (forced expiratory volume in 1 second)
  • Because this disease is progressive, younger people with CF generally have greater lung function than older people with CF
On average, lung function for a person with CF declines 1 to 3 percentage points each year.
Adapted from Cystic Fibrosis Foundation Patient Registry. 2013 Annual Data Report to the Center Directors. Bethesda, Maryland. © 2014 Cystic Fibrosis Foundation.
Adapted from Cystic Fibrosis Foundation Patient Registry. 2013 Annual Data Report to the Center Directors. Bethesda, Maryland. © 2014 Cystic Fibrosis Foundation.
In addition, obstruction in the airways, which can be caused by inflammation and scarring, can lead to pulmonary exacerbations. Pulmonary exacerbations are periods when symptoms get worse. Pulmonary exacerbations:
  • May cause permanent lung damage
  • May cause lung function to decline faster in people who have pulmonary exacerbations more frequently
With proper treatment, however, the progression of lung disease may be slowed, and the lungs may remain healthy for long periods of time.

Digestive System

Cystic fibrosis–related diabetes (CFRD)

The pancreas makes insulin, a hormone that helps the body manage sugar levels in the blood. If the body cannot do this, the person may develop diabetes.

As people with CF get older, they can develop a type of diabetes called cystic fibrosis–related diabetes, or CFRD. Because of CF, scarring of the pancreas may occur over time. As a result, the pancreas may not make enough insulin. In addition, the insulin that is produced may not be absorbed by the body. Some people with CFRD may need to drink more, use the bathroom more, feel very tired, lose weight, or have trouble gaining weight. They may also experience a decrease in lung function. Other people with CFRD may have no symptoms.

Though CFRD is a type of diabetes, it is a different condition than type 1 or type 2 diabetes.

Distal intestinal obstruction syndrome (DIOS)

DIOS in people with CF is a complete or incomplete blockage of the intestines. This can result from thick stool. DIOS is different from constipation. DIOS may be treated with medicine, enema, and/or diet. If the problem gets too severe, it may require surgery.

Other Parts of the Body

Cirrhosis of the liver

The liver has tubes called bile ducts that are meant to drain it of bile secretions. In people with CF, bile is thicker. Also, the tubes in which the bile travels can become blocked. Over time this may lead to irritation and scarring. This scarring can lead to cirrhosis, an advanced stage of liver disease. Cirrhosis makes it harder for blood to travel through the liver. This makes it harder for the liver to work properly.


In men: A man with CF can make sperm. However, the tubes through which the sperm need to pass may not have formed or may be clogged with mucus. Though intercourse is normal, a man with CF may deliver little or no sperm.

In women: For a woman who has CF, thick, sticky mucus in her reproductive system may make it difficult for sperm to travel to the uterus. This may make fertilization of a woman’s eggs difficult.

Bone density

Healthy bones require vitamin D. Vitamin D needs fat to be used by the body. Since people with CF have trouble absorbing fat, they may not have enough vitamin D for their bones. This can lead to a low bone density. This makes bones weak and can make bone fractures more likely.