| Achlorhydria | |
|---|---|
| Other names | Hypochlorhydria |
 | |
| Hydrogen chloride (major component ofgastric acid) | |
| Pronunciation | |
| Specialty | Internal medicine |
| Symptoms | Most of the time none, but may cause and not limited to, epigastric pain, other abdominal pain, unintentional weight loss,heartburn, nausea, vomiting, bloating, diarrhea, early satiety |
| Complications | Small intestinal bacterial overgrowth, nutrient deficiencies,gastric adenocarcinoma (rare), gastriccarcinoid tumor (rare) |
| Causes | Pernicious anemia,helicobacter pylori infection, hypothyroidism, gastric bypass surgery,VIPoma, chronicPPI use, gastric cancer, (rarely) radiotherapy |
| Treatment | Addressing underlying cause and managingSIBO and nutrient deficiencies |
Achlorhydria andhypochlorhydria are states where the production ofhydrochloric acid in gastric secretions of thestomach is absent or low, respectively.[1] Achlorhydria is commonly a complication of some other disease, such as chronicHelicobacter pylori infection or autoimmunepernicious anemia, as well as a possible side effect of long-term use of proton pump inhibitors.[2][3]
Complications of achlorhydria most frequently includesmall intestinal bacterial overgrowth and the nutritional deficiencies that can result from it. Rarely, achlorhydria may contribute to formation ofgastric cancers or gastriccarcinoid tumors.[4]
Irrespective of the cause, achlorhydria can result in known complications ofbacterial overgrowth andintestinal metaplasia, and symptoms are often consistent with those diseases:
Since acidic pH facilitates iron absorption, achlorhydric patients often developiron deficiency anemia.[5]
Bacterial overgrowth, the most frequent complication of achlorhydria, can cause micronutrient deficiencies such asB12 deficiency and other nutrient 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.[2][6] Nutritional deficiencies are the most common complication of achlorhydria.[2] Even without bacterial overgrowth, low stomach acid (high pH) can lead to nutritional deficiencies throughdecreased absorption of basic electrolytes (magnesium,zinc, etc.) and vitamins (includingvitamin C,vitamin K, and theB complex of vitamins).[citation needed]
Risk of particular infections, such asVibrio vulnificus (commonly from seafood) andVibrio cholerae is increased.[7]
Prevalence
Achlorhydria is present in about 2.5% of the population under 60 years old and about 5% of the population over 60 years old.[10][better source needed] The incidence increases to around 12% in populations over 80 years old. An absence ofhydrochloric acid increases with advancing age. A lack of hydrochloric acid produced by the stomach is one of the most common age-related causes of a harmed digestive system.[11]
Among men and women, 27% experience a varying degree of achlorhydria. US researchers found that over 30% of women and men over the age of 60 have little to no acid secretion in the stomach. Additionally, 40% of postmenopausal women have shown to have no basalgastric acid secretion in the stomach, with 39.8% occurring in females 80 to 89 years old.[11]
Comorbidities
Autoimmune disorders are also linked to advancing age, specificallyautoimmune gastritis, which is when the body produces unwelcome antibodies and causes inflammation of the stomach.[10][better source needed] Autoimmune disorders are also a cause for small bacterial growth in the bowel and a deficiency of Vitamin B-12. These have also proved to be factors of acid secretion in the stomach.[12] Autoimmune conditions can often be managed with various treatments; however, little is known about how or if these treatments effect achlorhydria.[10][better source needed]
Thyroid hormones can contribute to changes in the level of hydrochloric acid in the stomach, with unpredictable but strong fluctuations observed in states of bothhypothyroidism andhyperthyroidism.[13]
Long-term usage of medications or drugs
Extended use of antacids, antibiotics, and other drugs can contribute to hypochlorhydria.Proton pump inhibitors (PPIs) are very commonly used to temporarily relieve symptoms and conditions such as gastroesophageal reflux andpeptic ulcers.[12] Risk increases as these drugs are taken over a longer period, often many years, typically beyond the recommended therapeutic usage.
Stress can also be linked to symptoms associated with achlorhydria, including constant belching, constipation, and abdominal pain.[12]
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For practical purposes, gastric pH andendoscopy 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 anesophageal pH monitoring study.
Achlorhydria may also be documented by measurements of extremely low levels ofpepsinogen A (PgA) (< 17 µg/L) in blood serum. The diagnosis may be supported by high serumgastrin levels (> 500–1000 pg/mL).[14]
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, andthiamine.Complete blood count with indices and peripheral smears can be examined to excludeanemia. Elevation ofserumfolate is suggestive of small bowel bacterial overgrowth. Bacterial folate can be absorbed into the circulation.
Once achlorhydria is confirmed, ahydrogen breath test can check for bacterial overgrowth.
Treatment focuses on addressing the underlying cause of symptoms, as well as correction of any nutritional deficiencies, such as vitamin B-12 deficiency and thepernicious anemia that typically accompanies it.[2]
Achlorhydria associated withHelicobacter pylori infection may respond toH. pylori eradication therapy, although resumption of gastric acid secretion may only be partial, and it may not always reverse the condition completely.[15] Patients with known or suspectedH. pylori infection should be followed andendoscopically evaluated over time, due to the risk of recurrence as well as potential gastricmalignancy.[2]
Antimicrobial agents, includingrifaximin,metronidazole, amoxicillin/clavulanate potassium, ciprofloxacin, and others, can be used to treat bacterial overgrowth. Of these, rifaximin is the most well-studied and frequently used treatment for SIBO.[16]
Achlorhydria resulting from long-termproton-pump inhibitor (PPI) use may be treated by dose reduction or withdrawal of the PPI.[3]
Achlorhydria generally has a good prognosis, even after accounting for small intestinal bacterial overgrowth (SIBO). Aside from SIBO, the major risk of achlorhydria is the possibility of the development of gastric adenocarcinoma or gastric carcinoid tumor.[2]
SIBO is a chronic condition. Retreatment may be necessary once every 1–6 months.[17] Prudent use of antibacterials now calls for anantimicrobial stewardship policy to manageantibiotic resistance.[18]
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