Cystic fibrosis

Symptoms

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

Exams and Tests

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

References

US Food and Drug Administration. FDA Approves First DNA-based Test to Detect Cystic Fibrosis. Rockville, MD: National Press Office; May 16, 2005. Press Release P05-23.