Routine CF Testing 101

Last updated: September 2022

Every person with CF has a unique health journey and faces different challenges or complications along the way. No story is the same– but the basic testing done to keep individuals healthy and thriving can be very similar among the CF population.

In general, there are tests that are done to diagnose CF, certain routine tests completed at each CF clinic appointment, and tests completed yearly to screen for other complications. Again, your CF doctor may follow a different plan that best serves you as their patient. It’s important to talk about your routine testing needs with your CF clinic first and foremost.

However, if you are a family member new to the CF world and overwhelmed by all the information, or a seasoned vet who just wants to ensure you are up to date on your routine testing, this simple list might be a helpful tool for you!

What tests are used to diagnose CF?

There’s a few ways to screen and diagnose CF, especially beginning in young babies including: Newborn Screening (NBS) Test, Sweat Chloride Test, and CFTR genetic testing.

Newborn screening (NBS)

Since 2010, all 50 states have passed legislation to require newborn screening (NBS) for CF within the first few days of life.1 The NBS is an easy heel prick used to test for a chemical made in the pancreas called immunoreactive trypsinogen (IRT) in the blood. Some people have higher levels of IRT compared to others. If a baby comes back positive during the NBS, a sweat test is completed to confirm the child has CF.2

Completed: After birth

Sweat test

A sweat test is the gold standard way to diagnose CF. During a sweat test, electrodes are placed on the inside of the arm to cause the arm to sweat, the sweat is then collected and the sodium chloride levels are measured. A sweat chloride level ≥60 mmol/L is positive for CF.3

Completed: Between 10 days old and 4 weeks old for babies, and thereafter.4

Genetic testing

The third way it’s possible to diagnose CF is through genetic testing with a simple cheek swab or blood test. More than 1,800 mutations of the CF gene have been identified. If an individual has one copy of a CF causing mutation, they are considered a carrier of CF. Otherwise if an individual has two copies of CF-causing mutations, they have CF.5

Completed: Anytime

What tests are performed at each doctor appointment?

Typically CF clinic appointments follow a pretty standard schedule with a set of vitals, measurement of weight and height, and a pulmonary function test (PFT).

Height and weight

At each clinic appointment, height and weight are taken and followed closely. Height and weight are important measures of absorption, growth, and development, especially in young children with CF. Once you reach adulthood, height is not necessarily recorded each appointment.

Completed: Each clinic appointment

Vitals

Other vitals such temperature, blood pressure, and blood oxygen saturation help the CF care team keep close tabs on the general wellbeing of patients with CF. If vitals are outside your normal, they may help your CF team get to the root of the problem and develop a plan to get you better.

Completed: Each clinic appointment

Spirometry

Spirometry, or pulmonary function tests, are arguably the most important test completed at CF clinic appointments. In CF, spirometry focuses on FEV1 which measures how much air you can blow from your lungs in 1 second. FEV1 helps measure how well your lungs are working and tracks any changes in lung health.3

Completed: Each clinic appointment and more frequently during exacerbations

How were you diagnosed with CF? And what tests are preformed at a normal CF clinic visits for you? Share your experience below!

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