Testing for cystic fibrosis includes genetic screening, newborn screening, and sweat testing. A doctor can discuss the options with patients to determine the best choice for a given situation. In all cases, if the results are positive, a doctor will usually recommend follow-up and more testing to confirm the diagnosis and collect additional information. This information will be useful for managing a patient's cystic fibrosis.
Genetic screening consists of cystic fibrosis carrier testing, where parents receive a genetic test to see if they carry a copy of the gene associated with this disease. Cystic fibrosis is a recessive genetic disorder, and both parents need a copy of the gene for a child to develop the condition. Testing for cystic fibrosis can help parents determine if they are at risk of having a child with cystic fibrosis. If only one parent is a carrier, there is no cause for concern. If both are carriers, there is a 25% chance the child will have the disease.
After babies are born, parents can request newborn screening. This is a standard offering in many hospitals. A technician will prick the baby's heel to collect a small sample of blood and send it to a lab to screen for a variety of genetic conditions. Parents should be aware that a positive result on the newborn screening does not mean a baby has cystic fibrosis. It only indicates that she may have the disease, and another test is necessary to make a diagnosis.
The gold standard in testing for cystic fibrosis is the sweat test. People with cystic fibrosis produce an unusual amount of sodium chloride in their sweat. In the sweat test, the technician applies a chemical to make the patient sweat, and uses an electrode to gently stimulate the sweat glands and collect a sample. A lab analyzes the sweat to see how much sodium chloride is present. The results may be negative, positive, or indeterminate. If test results are unclear, the patient needs to repeat the test.
People considering testing for cystic fibrosis can receive it at most hospitals and clinics. If a facility cannot personally test samples, it can send them to a lab for analysis and return a result within days. Early diagnosis can be critical for providing interventions that will reduce a patient's risk of future complications. The advent of newborn testing for cystic fibrosis in many nations was a significant development in cystic fibrosis treatment, as it means that patients can start getting care before they develop symptoms.