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Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) Functional Assay (Quantitative Sweat Chloride Alternative)

Published: August 9, 2026Updated: August 16, 2026

This test measures the function of the CFTR protein, which helps regulate salt and water balance in cells. It’s used to diagnose cystic fibrosis or other conditions affecting CFTR function, often as a backup to sweat chloride testing.

Quick summary

["This test helps determine if your body’s CFTR protein is working properly, which may affect how you manage health conditions like cystic fibrosis or other genetic disorders."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
38452-9
Short code
CFTR c.3120+1G>A Bld/T Ql
Synonyms
CFTR c.3120+1G>A Bld/T Ql
Category
chemistry
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
molgen
Specimen volume
3 mL
Stability
Room temperature: 4h, Refrigerated: 24h
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

What This Test Measures

The test evaluates CFTR function indirectly by assessing its role in cell signaling and ion transport. Unlike sweat chloride testing, this method does not directly measure chloride ions in sweat but instead evaluates the protein’s biochemical activity in cells.

Why It’s Used

This test may be used when sweat chloride testing is unavailable, impractical, or when additional confirmation of CFTR dysfunction is needed. It’s particularly useful in research settings or for patients with rare genetic variations.

How the Test Works

Cells are exposed to specific stimuli that trigger CFTR activity. The test measures changes in cell responses, such as calcium signaling or ion flux, to assess whether the CFTR protein is functioning as expected.

What to Expect Before the Test

No special preparation is typically required, but your healthcare provider may ask about recent medications, infections, or dietary changes that could influence results. Blood or tissue samples are collected for analysis.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

CFTR Sweat Test Alternative

Frequently asked questions

How does this test differ from a sweat chloride test?
This test evaluates CFTR function through biochemical signaling rather than directly measuring chloride ions in sweat. Sweat chloride tests are more commonly used for diagnosing cystic fibrosis, while this method may be used for research, genetic testing confirmation, or alternative diagnostic approaches.
What if my test results are abnormal?
Abnormal results may indicate dysfunction in the CFTR protein, which could be linked to cystic fibrosis or other genetic conditions affecting ion transport. Your doctor will discuss next steps, such as further genetic testing or monitoring.
Can this test be done at home?
No, this test requires a laboratory setting and typically involves collecting blood or tissue samples. Home-based tests for CFTR function are not currently available.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

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.

Medical Disclaimer

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