Tests and Screening for the Cystic Fibrosis (CF) Patient
Important information:
Annual tests and screening tools help the CF care team learn how CF affects your child. Your CF care team will look at results from blood, X-ray, ultrasound, respiratory samples, and questionnaires. Results will be reviewed with you in clinic visits, or sooner if needed.
Blood tests
Complete blood count with differential (CBC with diff): Looks at the number and type of white blood cells, red blood cells, and platelets.
Comprehensive metabolic panel:
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Electrolytes: Measures sodium, potassium, and chloride levels.
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Blood urea nitrogen (BUN) and creatinine: Measures kidney function, which can be influenced by hydration and some medications.
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Glucose: Measures blood sugar.
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Total protein and albumin: Provides information regarding your child’s nutrition.
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Liver transaminases (AST, ALT and GGT), bilirubin and alkaline phosphate: Measures liver function.
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Prothrombin time (PT): Measures blood clotting, which is related to vitamin K.
Vitamins A, D, and E: Measures fat soluble vitamin levels.
Immunoglobulin E (IgE): Measures an immune response to allergens. This is measured once a year starting at 3 years old.
Hemoglobin A1C: Measures the average blood sugar for the past 3 months. It is used as a screening tool for diabetes once a year starting at 8 years old.
Oral glucose tolerance test (OGTT): This test is performed once a year on patients 8 years of age and older. OGTT is a 2-hour test that requires fasting. It checks to see if the body is using sugar the correct way.
Imaging
Chest X-ray: This is a tool used to follow lung disease in CF patients. The x-ray looks at two views: front-to-back and side-to-side (also known as AP and lateral). The amount of radiation is low. A pediatric radiologist reviews the x-ray and films are compared to previous ones to screen for changes in the lungs.
Liver ultrasound: This is an imaging test that uses high frequency sound waves to monitor the liver for CF-related changes. It’s recommended to perform every other year starting at 3 years old.
Elastography: This is an additional liver imaging test that uses high frequency vibrations to check the liver for stiffness. This is recommended for some patients with CF-related liver changes.
Respiratory tests
Pulmonary function tests (PFTs): The first set of PFT’s are done after your child turns four years old and then at every office visit. Children less than six years of age may find it difficult to perform this test. Repeated practice helps to improve the technique. PFTs look at:
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How much air can be blown out (exhaled) of the lungs
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How fast the air can be blown out (exhaled) of the lungs
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How the results change after your child inhales a bronchodilator (such as albuterol)
Respiratory culture: A respiratory culture helps to identify bacteria in the lungs. Identifying which bacteria is found helps to select the correct antibiotics for treatment. A culture will be grown in the lab over several days from mucous produced after coughing or a soft-cotton swab placed in the back of the throat.
Other tests
Pancreatic elastase: This test measures digestive enzymes secreted by the pancreas and helps us understand whether oral supplementation is required to digest fat from food and drinks.
Questionnaires/screening
Mental health screening: Starting at 12 years old, two questionnaires will be provided once a year to screen your child for anxiety and depression. Mental Health is tightly linked to physical health and the CF Team can provide appropriate resources to address anxiety and depression.
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Reviewed October 2024 by Mary Bridget Kastl, CRNP and Ambika Shenoy, MD