What Is Gastric Acid?

Gastric acid refers to the secretion of hydrochloric acid in gastric juice. The human stomach continues to secrete gastric acid, its basic excretion rate is about 10% of the maximum excretion rate, and it changes day and night. It reaches a peak a few hours after falling asleep, and it is the lowest before waking up in the morning. When food enters the stomach, gastric acid begins to be secreted. When the stomach is empty, the pH value is between 7.0 and 7.2. When the bolus enters the stomach, the pH value can drop between 2 and 3.

Basic Information

English name

gastric acid

Visiting department

Gastroenterology

Common locations

stomach

Contagious

no

The function of stomach acid

Pepsinogen in the stomach must first be activated by gastric acid and converted into pepsin and parapepsin. The most suitable pH for pepsin activation is about 2.0. At such a high acid concentration, pepsin will be activated and the protein will be digested and broken down. In addition, procarboxypeptidase in the intestinal pancreatic juice digestion protein system needs to be converted into carboxypeptidase that can digest proteins, and pepsin must be activated. Therefore, if gastric acid secretion is insufficient, pepsin cannot be produced, in addition to affecting the digestion of proteins in the stomach, it will also affect the further digestion of proteins in the intestine and the absorption and utilization of amino acids.

The amount of gastric acid cannot be too much or too small, and it must be controlled within a certain range, otherwise excessive gastric acid and insufficient gastric acid will occur.

When the stomach is too acidic, morbid symptoms such as "sour acid water", "heartburn", "faint stomach disease" will appear, which will seriously reduce appetite, indigestion, and then cause gastric ulcers and other forms of gastric disease. Hyperacidity is common in duodenal ulcers, gastrinoma, chronic gastritis, acute gastritis, reflux esophagitis, and cholecystitis.

Too little stomach acid means lack of hydrochloric acid in the stomach, that is, insufficient secretion of gastric juice, inability to take on the work of digestion and antiseptic fermentation, affecting digestion and absorption functions, susceptible to gastrointestinal diseases, and causing obstacles to digestion and absorption of nutrients. Many minerals and vitamins require sufficient concentrations of stomach acid for best absorption, such as iron, zinc, and B vitamins. Patients with gastric acid deficiency or gastric acid deficiency may have multiple nutritional deficiencies, and many health problems will occur, which will seriously affect people's health. Too little or no stomach acid, bacteria are prone to multiply in the stomach, more common in chronic atrophic gastritis, which can manifest as upper abdominal discomfort, poor appetite, and indigestion. The main symptoms of hypoacidity are gastric indigestion, snoring, and chest pain. Low gastric acid concentration in gastric juice may be caused by malignant anemia, tropical fatty diarrhea, and chronic gastritis.

Stomach acid is a double-edged sword. When it is secreted too little or lacking, it can cause indigestion such as bloating, diarrhea; too much secretion will invade the stomach and duodenal mucosa, and increase pepsin-induced ulcers. The effectiveness of this method directly leads to complications such as ulcer formation, ulcer perforation, and bleeding. In addition, high gastric acid can affect platelet aggregation and coagulation factor activity, making blood not easy to coagulate, leading to bleeding and rebleeding.

Determination of gastric acid

Pentagastrin was used as a stimulant, and the basic gastric fluid was periodically taken to measure the gastric acid secretion per unit time. Contains basal gastric acid secretion, maximum gastric acid secretion, and peak gastric acid secretion.

1. Basal acid output (BAO)

The total amount of gastric fluid secreted within 1 hour without food and drug stimulation was collected. Reference value: 3.9 ± 1.98mmol / L (rarely more than 5mmol / L)

2. Maximum gastric acid secretion (maximalacidoutput, MAO)

The pentagastrin stimulator was injected, and gastric juice was collected every 15 minutes, and the sum was measured 4 times in an hour. Reference value: 3 to 23 mmol / L (male), slightly lower for females.

3. Peak gastric acid secretion (peakacidoutput, PAO)

Take the sum of the two highest values in the measured MAO and multiply by two. Reference value: 20.60 ± 8.37mmol / L

There are many factors affecting gastric acid secretion. Although the specimen collection and test methods are satisfactory, this test can still be affected by the patient's gender, spirit, age, appetite, tobacco and alcohol. Therefore, the measurement of gastric acid secretion has a poor specificity for the diagnosis of diseases, and has certain significance only in the diagnosis of duodenal ulcer, gastrinoma, and gastric cancer.