The diagnosis of cystic fibrosis (CF) is usually based on high chloride concentrations in sweat, characteristic clinical findings (including sinopulmonary infections), and/or family history.
In these cases, a useful diagnostic adjunct involves measuring the nasal transepithelial potential difference (i.e. the charge on the respiratory epithelial surface as compared to interstitial fluid).
Individuals with cystic fibrosis have a significantly more negative nasoepithelial surface than normal, due to increased luminal sodium absorption.
[citation needed] Transepithelial / transendothelial electrical resistance (TEER) is an electrophysiological technique widely adopted for use in organ-on-a-chip systems.
Because it is non-invasive and offers the advantage of continuously monitoring living cells throughout their various stages of growth and differentiation, it is widely accepted as a standard validation tool.