There are a number of tests available to detect cystic fibrosis. Typically, the first diagnostic involves a blood test, which looks for differences in the CFTR gene. If CF runs in a patient’s family, a blood test is usually ordered as soon as possible, particularly in newborns who appear to be presenting with the disease. Early detection of CF can increase life expectancy as well as quality of life. Immunoreactive trypsinogen (IRT) is also available for newborns (another type of blood test). High levels of IRT may suggest Cystic Fibrosis as a possibility for CF-related symptoms. High salt levels in sweat is another sign of CF, which is also why doctors often order a sweat chloride test. Other CF tests include:
- Pulmonary function tests – This test measures how much air a person exhales, and how quickly.
- Chest X-ray – May show mucus densities in the airways.
- Fecal fat test – Measures the amount of fat in the stool to determine fat absorption, which indicates how well a person’s liver, gallbladder, pancreas and intestines are working.
- Pancreatic test – One such test measures fecal pancreatic elastase (an enzyme) to assess pancreatic function.
- Secretin stimulation test – This test measures how the pancreas responds to the hormone secretin. The upper part of the small intestine (duodenum) produces secretin when food enters the area. This causes the pancreas to release pancreatic juice (digestive enzymes) to break down food further and aid absorption. In CF, the pancreas is not releasing enough digestive enzymes.
- Trypsin/chymotrypsin test – This is a stool test that measures the amount of trypsin and/or chymotrypsin in fecal matter. Trypsin and chymotrypsin come from the pancreas so this measure pancreatic function. If the stool contains decreased amounts of these enzymes, that indicates pancreatic dysfunction.
- Upper GI and small bowel series – This is a set of X-rays taken of the esophagus, stomach and small intestine. This is done to see if there are any structural or functional abnormalities in these organs.
Click to read about Cystic Fibrosis Prognosis and Treatments.