Achlorhydria is decreased production of gastric acid by the stomach. Its main cause is antibody production against parietal cells, the cells that normally produce the acid, and is therefore an autoimmune disorder. It also occurs after long-term proton pump inhibitor therapy, or in patients with the rare disease mucolipidosis (type IV). It can be part of pernicious anemia, atrophic gastritis or of carcinoid of the stomach.

90% of all patients have detectable antibodies against the H+/K+ ATP-ase "proton pump".

The diagnosis is made if the gastric pH remains high (>4.0) despite maximum pentagastrin stimulation. High gastrin levels are often detected.

Achlorhydria leads to bacterial overgrowth since the disinfectant qualities of the gastric acid are too weak. This can lead to infections (such as with Vibrio vulnificus). Treatment focuses on replacing vitamin B12 (which is poorly absorbed in the absence of intrinsic factor) and avoiding foods that may be have a high bacterial load.

Sources

• Emedicine page on anchlorhydria