Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) Functional Assay (Plasma/Serum)
This test measures how well your CFTR protein works in your blood. CFTR is crucial for managing salt and water balance in cells, especially in lungs, intestines, and other organs affected by cystic fibrosis.
["Helps assess whether your cystic fibrosis symptoms may be linked to CFTR dysfunction."]
Key facts at a glance
- LOINC
- 53789-4
- Short code
- CFTRIVS8
- Synonyms
- CFTR IVS8 polyT 7T/9T Bld/T Ql
- Category
- chemistry
- Sample
- whole-blood
- Container
- EDTA (lavender-top) tube for whole blood; sterile container for tissue specimens
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- ≥ 0 years
- Method
- molgen
- CPT
- 81223
- SNOMED
- 40951-2
- Specimen volume
- 3-5 mL whole blood; 5 mg or more tissue
- Stability
- Whole blood: stable for 7 days at 2-8°C; freeze at -20°C or below for longer storage. Tissue: stable for 24 hours at 2-8°C; freeze at -80°C for prolonged storage. Avoid repeated freeze-thaw cycles; do not use formalin-fixed tissue for DNA analysis.
- Hemolysis max
- 0
- Lipemia max
- 0
- Icterus max
- 0
- TAT
- 72–336 hours
- Order
- routine
What This Test Measures
The test evaluates the functional activity of the CFTR protein using a specialized biochemical method. It detects how effectively CFTR regulates ion transport across cell membranes, which is essential for maintaining proper fluid balance in tissues.
Why It Matters in Cystic Fibrosis
CFTR dysfunction is a core cause of cystic fibrosis. Abnormal function can lead to thick, sticky mucus buildup in organs like the lungs and pancreas, causing respiratory and digestive issues. This test helps doctors determine if CFTR-related problems are contributing to your symptoms.
How the Test Works
Blood is drawn and analyzed to measure CFTR’s ability to transport chloride ions. The test may involve exposing cells to specific conditions to observe how CFTR responds, often using techniques like electrophysiological methods or biochemical assays.
Preparation for the Test
No special preparation is needed. You may eat and drink normally before the blood draw, but inform your doctor about any medications you’re taking, as some may affect results.
Reference range
Presence of IVS8 polyT variant (7T or 9T allele) reported as Detected or Not Detected. The 7T and 9T alleles are considered normal/non-classic CF variants; the 5T allele is associated with classic CF when present with a pathogenic CFTR mutation.N/A
No special preparation required. Patients should provide informed consent for genetic testing. Genetic counseling is recommended prior to and following testing. A complete family history and clinical evaluation are advised to support result interpretation.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Clinical Significance
Short name
CFTR Function Test
Frequently asked questions
How long will results take to return?
Can this test replace genetic testing for cystic fibrosis?
What if my results show abnormal CFTR function?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy