How Cystic Fibrosis is Diagnosed

The sweat test remains the most important and frequently used clinical test for the diagnosis of Cystic Fibrosis in South Africa. What is a sweat test? CF affects the exocrine glands. The sweat gland is a type of exocrine gland. CF causes an abnormal amount of salt to be lost in the sweat. The basis of the test is measuring the salt content in the sweat. If the child has CF, the analysis will show a high salt (sodium and chloride) level. This is a simple, painless and inexpensive test. However to be accurate it must be performed and interpreted correctly. It is important to keep in mind that the test does not give an indication of the severity of the disease. This test cannot be used to identify a carrier since they do not have CF and therefore have normal sweat glands. Individuals with cystic fibrosis can be diagnosed prior to birth by genetic testing and in overseas countries newborn screening tests are increasingly common. Due to the low numbers of affected people in South Africa, newborn screening tests are not performed unless there is a high risk of the child having CF.