CONVENTIONAL AND MODIFIED NASAL POTENTIAL-DIFFERENCE MEASUREMENT IN CYSTIC-FIBROSIS

Cystic fibrosis (CF) is associated with impaired ion transport across epithelial membranes and an increased transepithelial potential differ ence (PD) that can be measured in airway epithelium. The aim of this s tudy was to investigate the diagnostic value of nasal PD in CF, and to test a modified approach to the measurement of this PD. The reproduci bility and diagnostic sensitivity and specificity of nasal PD measurem ents were tested with the perfusion technique and with a simplified mo dification of the technique done with a novel, solid-state exploring e lectrode. With the perfusion method, basal PD values were different in CF patients (mean +/- SEM: -51.6 +/- 0.9 mV, n = 104) than in normal (-15.5 +/- 0.9 mV, n = 58, p < 0.01) subjects. CF patients with acute rhinitis or other nasal pathology had mean PD values that were interme diate between those of the patients and normal and disease-control gro ups (-28.3 +/- 1.2 mV, n = 40, p < 0.01, different from normal). The d iagnostic sensitivity of the perfusion method for CF was 91.3%, and th e specificity was 96.4%. PD measurements with the modified technique c orrelated highly with the results achieved with the perfusion method ( r = 0.94, n +/- 158). The measurement of nasal PD effectively distingu ishes CF from control subjects. Care must be taken in the interpretati on of measurements made on acutely inflamed epithelium. The modified m ethod was simpler than the conventional perfusion technique, and equal ly effective.