The pHmetry corresponds to the measurement of the acidity (pH) of a medium. In medicine, pHmetry is used to diagnose and assess the extent of gastroesophageal reflux disease (GERD). This is called esophageal pHmetry.

GERD is a condition in which the acidic contents of the stomach move up into the esophagus, which causes burns and can damage the lining of the esophagus. It is very common in infants and young children.

Esophageal pH-measurement is performed:

• to confirm the existence of gastroesophageal reflux disease (GERD);
• to look for the cause of atypical reflux symptoms, such as cough, hoarseness, sore throat, etc…;
• If anti-reflux therapy fails, to readjust treatment before anti-reflux surgery.

The test involves measuring the pH of the esophagus over a period of time (usually over a period of 18 to 24 hours). This pH is normally between 5 and 7; in GERD, very acidic stomach fluid moves up the esophagus and lowers the pH. Acid reflux is confirmed when the esophageal pH is below 4.

To measure intra-esophageal pH, a probes which will record the pH for 24 hours. This will make it possible to determine the severity of the reflux and its characteristics (day or night, correspondence with the symptoms felt, etc.).

It is generally required to be fasted for the exam. Anti-reflux therapy should be stopped several days before the test, as directed by the doctor.

The probe is introduced through a nostril, sometimes after nasal anesthesia (this is not systematic), and it is gently pushed through the esophagus to the stomach. To facilitate the progress of the catheter, the patient will be asked to swallow (for example by drinking water through a straw).

The probe is attached to the wing of the nose with a plaster and connected to a recording box which is worn on the belt or in a small bag. The patient can then go home for 24 hours, following their usual activities and eating normally. The catheter is not painful, but it can be slightly bothersome. It is asked to note the times of the meals and the possible symptoms felt. It is important not to get the case wet.

The doctor will analyze the pH measurement to confirm the presence and severity of gastroesophageal reflux disease (GERD). Depending on the results, appropriate treatment may be offered.

GERD can be treated with anti-reflux medications. There are many, such as proton pump inhibitors or H2 blockers.