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. It is associated with various other medical problems. Signs and symptoms
Irrespective of the cause, achlorhydria can result as known complications of bacterial overgrowth and intestinal metaplasia and symptoms are often consistent with those diseases:

gastroesophageal reflux disease
abdominal discomfort
early satiety
weight loss
diarrhea
constipation
abdominal bloating
anemia
stomach infection
malabsorption of food
carcinoma of stomachSince acidic pH facilitates the absorption of iron, achlorhydric patients often develop iron deficiency anemia. 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. Risk of particular infections, such as Vibrio vulnificus (commonly from seafood) is increased. Even without bacterial overgrowth, low stomach acid (high pH) can lead to nutritional deficiencies through decreased absorption of basic electrolytes (magnesium, zinc, etc.) and vitamins (including vitamin C, vitamin K, and the B complex of vitamins). Such deficiencies may be involved in the development of a wide range of pathologies, from fairly benign neuromuscular issues to life-threatening diseases.
Diagnosis
For practical purposes, gastric pH and endoscopy should be done in someone with suspected achlorhydria. 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. A complete 24-hour profile of gastric acid secretion is best obtained during an esophageal pH monitoring study. Achlorhydria may also be documented by measurements of extremely low levels of pepsinogen A (PgA) (< 17 µg/L) in blood serum. The diagnosis may be supported by high serum gastrin levels (> 500–1000 pg/mL).The "Heidelberg test" is an alternative way to measure stomach acid and diagnose hypochlorhydria/achlorhydria. A check can exclude deficiencies in iron, calcium, prothrombin time, vitamin B-12, vitamin D, and thiamine. Complete blood count with indices and peripheral smears can be examined to exclude anemia. Elevation of serum folate is suggestive of small bowel bacterial overgrowth. Bacterial folate can be absorbed into the circulation. Once achlorhydria is confirmed, a hydrogen breath test can check for bacterial overgrowth. Treatment
Treatment focuses on addressing the underlying cause of symptoms. Treatment of gastritis that leads to pernicious anemia consists of parenteral vitamin B-12 injection. Associated immune-mediated conditions (e.g., insulin-dependent diabetes mellitus, autoimmune thyroiditis) should also be treated. However, treatment of these disorders has no known effect in the treatment of achlorhydria.