Cystic Fibrosis Diagnosis: An Overview of Diagnostic Methods

Patient and technician at a CT scan machine

Cystic fibrosis (CF) is a genetic condition that can affect the patient’s lungs and other organs. According to the Cystic Fibrosis Foundation Patient Registry, nearly 40,000 patients in the U.S. are currently living with the disease. Over 75% of these cases are diagnosed by the time the patient turns 2; however, some patients won’t be officially diagnosed until adulthood.

This article provides an overview of the disease, focusing on diagnostic methods and techniques, including genetic testing, sweat tests, and the role of medical imaging.

What is cystic fibrosis?

For patients with CF, mutations in their cystic fibrosis transmembrane conductance regulator gene, also called the CFTR gene, can affect their CFTR protein functionality. When this happens, the protein may not reach the cell surface or may function improperly once there. Its role is to move chloride to the surface of the cells. Normally, the chloride would attract water to the surface of the cell as well, but without it, the body produces glue-like mucus in various organs, which can lead to complications.

While the lungs are often the most affected organs, other regions, such as the pancreas, can also be impacted. Here are some ways this inherited condition can affect patients:

Lung complications: Germs and bacteria can become trapped in the patient’s airways due to thick mucus clogging internal structures. This makes them more prone to illness, infections, respiratory issues and other problems.
Digestive issues: Due to mucus buildup in the pancreas, digestive enzymes may be unavailable to aid in nutrient absorption. This can lead to malnutrition and growth impacts.
Liver disease: The glue-like mucus can also obstruct the bile duct, leading to liver disease.
Reproductive problems: It is common for CF patients assigned male at birth (AMAB) to have difficulties reproducing. Fortunately, experienced fertility specialists have successfully assisted many CF patients with this endeavor.

Cystic fibrosis and genes

Cystic fibrosis is caused when two copies of the mutated CF gene are inherited from both parents. When a person has only one of these mutated genes, they are considered a carrier. They do not have CF, but they can pass the gene down to their offspring if their partner also carries a mutated CF gene. The chances of two carriers passing on this condition to their children are as follows:

Every time they have a child together, there is a 1 in 4 chance (25%) that the child will have cystic fibrosis.
With each child born, there is a 1 in 4 chance (25%) that the child will neither have cystic fibrosis nor be a carrier.
There is a 1 in 2 (50%) chance that the child will be a carrier for cystic fibrosis but will not have the disease.

Outlook for cystic fibrosis

In the past, CF patients had a short lifespan due to complications of the disease. In recent years, however, medical treatments and advancements have significantly improved the outlook for patients. The current estimated median age of survival for CF patients born between 2020 and 2024 is 65 years. It is important to note that this is an estimated median and is not an accurate prediction on an individual basis. Some patients are currently living rich lives well into their 70s and 80s.

Prognosis and outlook vary significantly on a case-by-case basis, with factors such as disease severity, treatment methods and individual health playing a large part in life expectancy. CF still has significant impacts on many patients’ lifespans, and it continues to be studied. However, advancements in treatments and management continue to progress, especially in promising fields such as gene replacement therapy.

Symptoms of cystic fibrosis

Symptoms of CF may vary from patient to patient, with underlying health and disease severity being important factors in how the condition manifests. Here are some common cystic fibrosis symptoms:

Recurring sinus infections
Infertility in AMAB patients
Chronic cough
Recurring lung infections, bronchitis or pneumonia
Difficulty breathing or shortness of breath
Clubbing of toes and fingers
Decreased growth due to malnutrition
Nasal polyps
Bowel issues and greasy stools
Prolapse of the rectum
Excessively salty-tasting skin

It is important to note that experiencing these symptoms does not necessarily mean you have CF. There are numerous milder conditions that may cause similar symptoms. It’s recommended to discuss any concerns with your doctor so they can take the next steps and address your health on an individual basis.

How cystic fibrosis is diagnosed

CT scan of the chest organs

Here is an overview of diagnostic methods for cystic fibrosis.

Newborn Screening

In the U.S. and Canada, newborn screening is a standard practice to help detect various health conditions and diseases after a baby is born, including cystic fibrosis. A heel prick is performed, and a small blood sample is taken for analysis. If the report shows higher than expected levels of an enzyme called immunoreactive trypsin, it can indicate issues with the pancreas, which may point to CF. However, these elevated levels can occur for other reasons, such as a stressful birth, being a CF carrier or other less serious causes.

Additionally, some regions commonly test for the gene mutation deltaF508, which is the most frequent mutation found in 70% of CF patients. If abnormalities are detected in either test, the test is typically repeated, as false positives can occur due to other factors. If the second round of testing still shows signs of CF, additional testing will likely be performed.

Genetic testing

There are over 2,000 known mutations of the CF gene that the medical community is currently aware of. Genetic testing can help identify these mutations in many cases, revealing the risk for cystic fibrosis. For couples wanting to conceive, it can be helpful to undergo this testing in advance to determine if they are carriers of the condition. It is estimated that there are over 10 million carriers in the U.S. alone, making it an important step in pregnancy planning.

For patients being tested for CF, genetic tests can be very helpful in reaching a diagnosis, as they can often pinpoint the precise gene mutation that indicates the presence of the disease.

Sweat test

The “sweat test” is the standard method for diagnosing cystic fibrosis. It is often performed after other tests, such as genetic screening, suggest the possibility of CF. Patients with cystic fibrosis tend to have higher levels of chloride (salt) in their sweat. A chemical is applied to the patient’s skin, typically on the arm or leg, and a painless electric current is used to stimulate sweating. A sample is then collected and tested for chloride levels.

Some specific CF mutations may not cause increased chloride levels, but in the majority of cases, the sweat test remains a highly reliable diagnostic tool.

Nasal lining measurements

This test is also called the nasal potential difference (NPD). Due to issues with chloride transport caused by the mutated CFTR protein, sodium and chloride ions behave differently in patients with CF. Specifically, there is a reduction in chloride transport and an increase in sodium absorption.

While the lungs are commonly affected, the cell surfaces of the nasal lining can be used to measure airway ion transport. This is done using a painless electric current along with various solutions to stimulate ion movement. The resulting voltage changes are collected and evaluated against expected baselines.

Medical imaging

While medical imaging cannot officially diagnose cystic fibrosis, it can play an important role in assessing organ function, tracking disease progression and evaluating overall health. Here are some common imaging modalities that may be used for CF patients:

CT scan: Computed tomography uses X-rays to create internal images of the body. Unlike standard X-rays, CT scans take multiple cross-sectional “slices,” which are compiled to form a highly detailed view. CT scans can help identify abnormal mucus, dilated airways, infections, lung disease and sinus polyps, which are common in CF patients.
MRI scan: Magnetic resonance imaging uses radio waves and strong magnets to create detailed images of tissues, bones and organs. Like CT scans, MRIs are used to assess potential damage or complications related to CF, but they are not used to make a diagnosis on their own.
Ultrasound: Ultrasound imaging uses high-frequency sound waves that bounce off internal structures and echo back to produce images. It can help assess function in organs such as the liver and pancreas, which are commonly affected by CF.

Getting your results

Turnaround times for imaging results can vary widely depending on the facility and your doctor’s availability. Often, patients wait a week or more and receive their results during a follow-up appointment. With PocketHealth, you don’t have to wait as long—your imaging results are securely accessible as soon as the report is available, allowing you to review them often before your follow-up visit.

Your imaging results are interpreted by a radiologist—an expert in medical imaging—who carefully reviews your scans and provides a detailed report of any findings. This report is then sent to your referring doctor, who, with a deeper understanding of your medical history, can offer further insights and recommendations.

To better understand your imaging reports, Report Reader provides clear, straightforward definitions for medical terms. Simply tap or click on any underlined words to reveal their meaning. This is paired with illustrations and highlights of anatomy in your imaging to help you better understand your results and prepare for follow-up appointments.

Frequently asked questions

Here are some common questions regarding cystic fibrosis.

What are the symptoms of cystic fibrosis in adults?

While the majority of CF cases are discovered in infancy or by the age of 2, there are cases that remain undetected until adulthood. In these cases, symptoms may include:

Inflammation of the pancreas
Arthritis
Infertility in AMAB patients
Wheezing and breathing difficulties
Chronic cough
Malnutrition
Recurring lung infections and issues
Sinusitis

What is the treatment for cystic fibrosis?

There are several treatments for cystic fibrosis patients, which may vary depending on how advanced the disease is. Some may include:

Airway clearance techniques (ACT): These methods help loosen the glue-like mucus so the patient can cough it out. Breathing exercises and specific techniques assist with this process, allowing the patient to breathe more easily and reducing the risk of infection.
Avoidance practices: CF patients are at higher risk for respiratory issues and infections. Because of this, it is often recommended that they avoid secondhand smoke and exposure to contagious illnesses.
PEP devices: Positive expiratory pressure (PEP) devices are used in the patient’s mouth to help them exhale forcefully, making it easier to push mucus out of the airways.
Chest therapy: This can be done manually or with the use of a therapy vest. The chest wall is vibrated or shaken to help loosen mucus from the lungs and airways.
Medications: A variety of medications may help ease a patient’s symptoms. Examples include mucus thinners, bronchodilators to improve airway function and CFTR modulators, which enhance gene function in patients with specific genetic mutations.
Breathing therapies: These may include ventilators or oxygen therapy to support respiratory function.
Surgery: In advanced cases, liver or lung transplants may be necessary to improve health and restore organ function.

Can cystic fibrosis be prevented?

The only way cystic fibrosis can currently be prevented is through genetic testing and pregnancy planning. Couples wanting to conceive can be tested to determine if they are carriers of CF. If both partners carry the mutated CF gene, they may want to consult a fertility specialist to discuss next steps and possible alternatives. Because it is an inherited condition, this remains the only available method of prevention.

What are some myths about cystic fibrosis?

There are some common misconceptions about cystic fibrosis that may be helpful to clarify:

It is a disease only found in children: Most new cases of CF are diagnosed in childhood, thanks to early screenings and increased awareness. However, adults can still be diagnosed later in life.
It is only a lung disease: In reality, cystic fibrosis can affect multiple organs, including the pancreas and liver.
It is a form of asthma: CF is not asthma, though both conditions can impact breathing. In CF, the airways are obstructed by thick mucus, while asthma is caused by inflammation of the airways.
A lung transplant cures CF: Because CF affects the entire body, a lung transplant does not cure the condition. However, it can significantly improve respiratory symptoms and may prolong the patient’s lifespan.

Getting support

A cystic fibrosis diagnosis can feel overwhelming, but it’s important to know you’re not alone. As therapies and treatments continue to advance, so do the support systems available to patients. Your doctor will likely provide local resources and education. In the meantime, here are some online resources that patients may find helpful:

Take control of your health journey

PocketHealth makes it simple to keep track of your medical imaging. All of your vital imaging is in one secure location and can be accessed online anytime. Reports can also be easily shared with other physicians in your care team, if needed. Additionally, it makes it easy to track health changes over time, such as with repeat imaging. When used in conjunction with your medical provider’s professional advice, it is a powerful tool for organizing and understanding your imaging results and your health.

PocketHealth MyCare Navigator gives personalized insights into your health and identifies any recommended follow-up steps. This feature can also generate individualized questions to ask your doctor based on the findings in your report, ensuring you make the most of your consultation. A cystic fibrosis diagnosis may feel overwhelming, but working closely with your providers can give you the best chance of managing your condition and protecting your health.