Diagnosis
Cystic Fibrosis

In some newborns, the first sign of CF is a meconium ileus, (meh-KOH-nee-um ILL-ee-us), a condition in which a baby has an obstruction of the intestines at birth. More often, doctors begin to suspect a child has CF because of coughing or lung infections, or an inability to gain weight.

In eight of the United States, Australia and France, newborns are automatically screened for CF. A small sample of blood is tested on a special card. If the card shows a positive result, doctors do more tests to confirm the diagnosis. More states are planning to enact such screening in the future.

Amniocentesis (am-nee-oh-sen-TEE-sis) or chorionic villi (kor-ee-ON-ick VILL-eye) testing can be used to test for CF mutations before birth. Another genetic test, called buccal (BUKE-ul) cell collection, uses a cheekbrush or special mouthwash to collect cells for genetic testing. However, these tests can miss many CF cases, because so many CF mutations haven't been discovered yet and because the tests aren't very sensitive.

An experimental test that detects sulfur compounds in exhaled air may prove a much better screening method. Because bacteria produce these sulfur compounds, people with CF appear to have higher levels of the compounds on their breath -- even before the bacteria make them sick. Such a breath test may help identify infections sooner, when they are easier to treat.

Final diagnosis of CF today centers on the sweat test. Because CF causes imbalances of salt in the body, it leads to particularly salty sweat. In the sweat test, doctors give patients the drug pilocarpine (pie-loh-KARP-een), and then send the sweat to a lab to be chemically measured for sodium chloride.




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