Achlorhydria and hypochlorhydria refer to states where the production of hydrochloric acid in gastric secretions of the stomach and other digestive organs is absent or low, respectively.

The acidic environment of stomach helps conversion of pepsinogen into pepsin, which is highly important in digesting the protein into smaller components, such as a complex protein into simple peptides and amino acids inside the stomach, which are later absorbed by the gastrointestinal tract.

Bacterial overgrowth and B12 deficiency (pernicious anemia) can cause micronutrient deficiencies that result in various clinical neurological manifestations, including visual changes, paresthesias, ataxia, limb weakness, gait disturbance, memory defects, hallucinations and personality and mood changes.

Even without bacterial overgrowth, low stomach acid (high pH) can lead to nutritional deficiencies through decreased absorption of basic electrolytes (magnesium, zinc, etc.)

Such deficiencies may be involved in the development of a wide range of pathologies, from fairly benign neuromuscular issues to life-threatening diseases.

Additionally, 40% of postmenopausal women have shown to have no basal gastric acid secretion in the stomach, with 39.8% occurring in females 80 to 89 years old.

Proton pump inhibitors (PPIs) are very commonly used to temporarily relieve symptoms conditions such as gastroesophageal reflux and peptic ulcers.

[7] Risk increases as these drugs are taken over a longer time period, often many years, typically beyond the recommended therapeutic usage.

Older testing methods using fluid aspiration through a nasogastric tube can be done, but these procedures can cause significant discomfort and are less efficient ways to obtain a diagnosis.

Bacterial overgrowth may cause false-positive H. pylori test results due to the change in pH from urease activity.