How should be teseted for cystic firbrosis?

Answer 1

Most people are diagnosed with CF at birth through newborn screening, or before the age of 2. A Doctor Who sees the symptoms of CF will order a sweat test or a genetic test to confirm the diagnosis.

A sweat test is the most common test used to diagnose cystic fibrosis and is considered the diagnostic "gold standard." A small electrode is placed on the skin (usually on the arm) to stimulate the sweat glands. Sweat is then collected and the amount of chloride, a component of salt in the sweat, is measured. A high level of chloride means that the person has cystic fibrosis.

For children who are less than six months old:

• Chloride levels at or above 60 mmol/L (a measure of concentration) means the child has CF.
• Chloride levels between 30 and 59 mmol/L are considered borderline and need to be examined on a case-by-case basis.
• Chloride levels below 30 mmol/L are considered negative for CF.

For people over the age of six months:

• Chloride levels at or above 60 mmol/L means the person has CF.
• Chloride levels between 40 and 59 mmol/L are boderline.
• Chloride levels below 40 mmol/L are considered negative for CF.

The best place to receive a reliable sweat test is at a Cystic Fibrosis Foundation-accredited care center.

In a genetic test, a blood sample or cells taken from the inside of the cheek are sent to a laboratory that specializes in genetic testing. Most labs only test for the most common mutations of the CF gene. Because there are more than 1,000 mutations that cause CF, screening for all mutations is not possible. A genetic test is often used if the results from a sweat test are unclear.