Cystic fibrosis is an inherited disease that causes thick, sticky mucus to build up in the lungs and digestive tract. It is the most common type of chronic lung disease in children and young adults, and may result in early death.  

Cystic fibrosis (CF) is caused by a defective gene which tells the body to produce abnormally thick and sticky fluid, called mucus. This mucus builds up in the breathing passages of the lungs and the pancreas, the organ that helps to break down and absorb food.

This collection of sticky mucus results in life-threatening lung infections and serious digestion problems. The disease may also affect the sweat glands and a man's reproductive system.

Millions of Americans carry the defective CF gene, but do not have any symptoms. That's because a person with CF must inherit two defective CF genes -- one from each parent. An estimated 1 in 29 Caucasian Americans have the CF gene. The disease is the most common, deadly, inherited disorder affecting Caucasians in the United States. It's more common among those of Northern or Central European descent.

Most children are diagnosed with CF by their 2nd birthday. A small number, however, are not diagnosed until age 18 or older. These patients usually have a milder form of the disease.

Because there are more than 1,000 mutations of the CF gene, symptoms differ from person to person. But in general they include:

• No bowel movements in first 24 to 48 hours of life
• Stools that are pale or clay colored, foul smelling, or that float
• Infants may have salty-tasting skin
• Recurrent respiratory infections, such as pneumonia or sinusitis
• Coughing or wheezing
• Weight loss, or failure to gain weight normally in childhood
• Diarrhea
• Delayed growth
• Fatigue

A blood test is available to help detect CF. The test looks for variations in a gene known to cause the disease. Other tests use to diagnose CF include:

• Immunoreactive trypsinogen (IRT) test. This is a standard newborn screening test for CF. A high level of IRT suggests possible CF and requires further testing.
• Sweat chloride test. This is the standard diagnostic test for CF. A high salt level in the patient's sweat indicates the disease.
• Fecal fat test
• Upper GI and small bowel series
• Measurement of pancreatic function

Cystic fibrosis may alter the results of the following tests:

• Trypsin and chymotrypsin in stool
• Secretin stimulation test
• Chest x-ray or CT scan
• Lung function tests