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Diagnostic Tests for Cystic Fibrosis

Cystic Fibrosis: Diagnostic Tests

The list of diagnostic tests mentioned in various sources as used in the diagnosis of Cystic Fibrosis includes:

Home Diagnostic Testing

These home medical tests may be relevant to Cystic Fibrosis:

Tests and diagnosis discussion for Cystic Fibrosis:

NHLBI, Facts About Cystic Fibrosis: NHLBI (Excerpt)

The most common test for CF is called the sweat test. It measures the amount of salt (sodium chloride) in the sweat. In this test, an area of the skin (usually the forearm) is made to sweat by using a chemical called pilocarpine and applying a mild electric current. To collect the sweat, the area is covered with a gauze pad or filter paper and wrapped in plastic. After 30 to 40 minutes, the plastic is removed, and the sweat collected in the pad or paper is analyzed. Higher than normal amounts of sodium and chloride suggest that the person has cystic fibrosis.

The sweat test may not work well in newborns because they do not produce enough sweat. In that case, another type of test, such as the immunoreactive trypsinogen test (IRT), may be used. In the IRT test, blood drawn 2 to 3 days after birth is analyzed for a specific protein called trypsinogen. Positive IRT tests must be confirmed by sweat and other tests.

Also, a small percentage of people with CF have normal sweat chloride levels. They can only be diagnosed by chemical tests for the presence of the mutated gene. Some of the other tests that can assist in the diagnosis of CF are chest x-rays, lung function tests, and sputum (phlegm) cultures. Stool examinations can help identify the digestive abnormalities that are typical of CF. (Source: excerpt from NHLBI, Facts About Cystic Fibrosis: NHLBI)

NHLBI, Facts About Cystic Fibrosis: NHLBI (Excerpt)

Finding out whether a baby is likely to have CF is possible using prenatal genetic tests. However, the tests cannot detect all of the CF gene mutations. Also, because these tests are very expensive and have certain risks to the mother, they are not used for all pregnant women. If there is another child with CF in the family, the expectant mother may request a prenatal test to see if the fetus has CF genes from both parents, is a carrier for one gene, or is altogether free of the CF genes.

There are two special prenatal tests that can be done--either an amniocentesis or chorionic villus biopsy will be performed. In amniocentesis, cells from the fluid surrounding the baby in the mother's womb (called the amniotic fluid) are tested to see if the CF genes common to the parents are present. In chorionic villus biopsy, cells from the tissue that will eventually form the placenta are tested for the CF gene. (Source: excerpt from NHLBI, Facts About Cystic Fibrosis: NHLBI)

Diagnosis of Cystic Fibrosis: medical news summaries:

The following medical news items are relevant to diagnosis of Cystic Fibrosis:

 

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