What is a nasal potential difference measurement?

The Nasal potential difference measurement is used to measure the voltage across the nasal epithelium, which results from transepithelial ion transport and reflects in part CFTR function.

What is a nasal PD?

The nasal PD (NPD) is a sensitive test of electrolyte transport that can be used to support or refute a diagnosis of CF. A normal mean value standard error (SE) is 0.9-24.7 mV; an abnormal value is 1.8-53 mV.

What is a positive sweat chloride test?

A positive sweat chloride test indicates that it is likely that the infant or person tested has cystic fibrosis (CF). Positive sweat chloride tests are typically repeated for verification. The results may also be confirmed by CF gene mutation panel testing.

How is potential difference measured in the nose?

Nasal potential difference measurement will be obtained to potentially help aid in diagnosis. Nasal potential difference measurement involves dripping small amounts of 5 test solutions into the anterior nostril.

How is nasal potential difference ( NPD ) used in CF diagnosis?

Nasal epithelial CFTR function will be assessed by the NPD procedure. NPD measurements are useful as a diagnostic tool in individuals with borderline or normal sweat chlorides, one or no identified CFTR mutations, and a clinical history suggestive of CF.

How are NPD levels measured in the nose?

NPD is measured using a device called a voltmeter, which records the potential difference across the epithelial membrane of the nose. Three electrodes are used for the measurement to be taken. One of these electrodes is placed on the surface of nasal mucosa or mucous membrane lining the nasal cavities.

Can a nasal potential difference test be unreliable?

The test is unreliable in case of inflammation or nasal infections such as sinusitis or acute rhinitis. Treatments such as inhaled therapies with hypertonic saline, antibiotics, amiloride, and DNase tend to normalize the potential difference in CF and make results unreliable.