Neonatal cystic fibrosis screening test

Neonatal Cystic Fibrosis Screening Test

Neonatal cystic fibrosis (CF) screening is a genetic test used to identify newborns who may have inherited the disorder. It is recommended for all newborns in the United States, as it is widely available and ethically acceptable. In some countries, neonatal screening is a legal requirement.


Neonatal CF screening typically takes place soon after birth, usually within the first 48 hours or before the baby leaves the hospital. The test is usually done on a blood sample taken from the baby's heel, so there is no need for special preparation.


The collected sample is sent to a laboratory for analysis. The laboratory looks for abnormal levels of certain substances in the baby's body, focusing particularly on electrolytes that are present in the sweat of babies with CF. These substances, which include chloride and sodium, are measured and compared to the results of healthy babies of the same age.


CF screening can be done by either immunoreactive trypsinogen (IRT) or genetic DNA analysis. IRT is the most commonly used test, as it requires a blood sample and does not involve a genetic analysis of the baby's DNA. The genetic DNA analysis is a more accurate, but more expensive, test, which requires a sample of the baby's saliva or blood to be sent to a laboratory for analysis.


Neonatal CF screening is considered a safe and low-risk test that does not cause any discomfort to the baby. The heel prick sample may cause some minor discomfort, but it generally does not cause pain.

Why it is important?

Neonatal CF screening is important because it can detect CF in babies from a very young age, before any signs or symptoms of the condition are present. Early diagnosis and treatment can greatly improve health outcomes for people with CF. It is important to remember that neonatal CF screening is offered as an option to parents, and is not a legal requirement.

When to do it?

Neonatal CF screening is typically done soon after birth, usually within the first 48 hours or before the baby leaves the hospital. Some states require the test to be done before the baby leaves the hospital, while other states recommend it but do not require it.


  • CF affects approximately 30,000 people in the United States.
  • CF is caused by a mutation in the cystic fibrosis transmembrane conductance regulator (CFTR) gene.
  • The most common CF-causing mutation is F508del, which is present in 70 percent of CF cases.
  • CF is a genetic disorder, meaning it is inherited from one’s parents. A baby must inherit two faulty Copies of the CFTR gene (one from each parent) to have CF.
  • There are more than 1300 mutations known to cause cystic fibrosis.