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:
- Lung & Respiratory Health Tests:
Cystic Fibrosis Diagnosis: Book Excerpts
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
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