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Updated: Apr 6, 2026
Standardized Measurement of Nasal Membrane Transepithelial Potential Difference NPD
Published on: September 13, 2018
A semi-blinded study comparing 2 methods of measuring nasal potential difference: Subcutaneous needle versus dermal
E De Wachter1, I De Schutter1, A Meulemans2
1CF Clinic, Universitair Ziekenhuis Brussel, Vrije Universiteit Brussel, Brussels, Belgium.
Background:
According to European and US protocols, two nasal potential difference (NPD) measurement methods are considered acceptable, although they have not been formally compared: subcutaneous agar-filled needle with calomel (Ndl) and dermal abrasion with conducting cream and Ag/AgCl electrodes (Abr). We compared both in CF and healthy volunteers (HV), assessing their discriminative value and subject's preference.
Methods:
Twelve classic CF and 17 HV underwent both NPD methods, performed by one operator in random order. A written questionnaire, assessing preference, was completed after each test. Tracings were coded, scored in a semi-blinded fashion and categorised as CF/non-CF.
Results:
110 tracings (56 Ndl/54 Abr) were collected: 42/110 scored CF and 68/110 non-CF, showing a good correlation. No significant preference for either method was reported.
Conclusion:
Both NPD methods are similar in terms of discriminative value and subject's preference, comparing classical CF and HV. For diagnosing CF, the operator's preferred NPD-method may be used.
