Potential Difference Measurement
Intestinal current measurement (ICM) is an examination, in which the chloride transport in the body is determined by measuring the potential difference in nasal or rectal mucosa. This examination is conducted in patients with cystic fibrosis (CF).
In case of cystic fibrosis, there are problems in the transport of chloride in the body. Intestinal current measurement is performed in those cases where the outcome of the sweat test is not clear and DNA tests provide no certainty about the diagnosis of CF as well.
Chloride transport is measured by electric currents in very small pieces of tissue. For this purpose, it’s necessary to take pieces of tissue (biopsies) from the rectum. The measurements are carried out in the laboratory.
Since four measurements are done simultaneously, there are also four biopsies taken. This examination is similar to inserting a thermometer. Because this part of the intestine has no pain nerves, the patient feels no pain. In a single case, there is a trace of blood loss after the intervention.
The potential difference in the nasal mucosa is determined by inserting a small tube into the nose. This causes a tickling sensation. A measurement lasts about a quarter of an hour and takes place in both nostrils.