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an abnormal deficiency or absence of free hydrochloric acid in the gastric juice; often associated with severe anemias and cancer of the stomach

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/06/25 23:42:27」(JST)

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Achlorhydria /eɪklɔərˈhaɪdriə/ or hypochlorhydria refers to states where the production of hydrochloric acid in gastric secretions of the stomach and other digestive organs is absent or low, respectively.^[1] 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

Since acidic pH facilitates the absorption of iron, achlorhydric patients often develop iron deficiency anemia.

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, should also be obtained.

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.

Causes

The slowing of the body's basal metabolic rate associated with hypothyroidism
Pernicious anemia where there is antibody production against parietal cells which normally produce gastric acid.
The use of antacids or drugs that decrease gastric acid production (such as H2-receptor antagonists) or transport (such as proton pump inhibitors).
A symptom of rare diseases such as mucolipidosis (type IV).
A symptom of Helicobacter pylori infection which neutralizes and decreases secretion of gastric acid to aid its survival in the stomach.^[2]
A symptom of atrophic gastritis or of stomach cancer.
Radiation therapy involving the stomach.
Gastric bypass procedures such a duodenal switch and RNY, where the largest acid producing parts of the stomach are either removed, or blinded.
VIPomas (vasoactive intestinal peptides) and somatostatinomas are both islet cell tumors of the pancreas.
Pellagra, caused by niacin deficiency.
Chloride, sodium, potassium, zinc and/or iodine deficiency, as these elements are needed to produce adequate levels of stomach acid (HCl).

Diagnosis

For practical purposes, gastric pH at 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 mcg/L) in blood serum. The diagnosis may be supported by high serum gastrin levels (>500-1000 pg/mL).^[3]

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.

Achlorhydria associated with Helicobacter pylori infection may respond to H pylori eradication therapy, although resumption of gastric acid secretion may only be partial and it may not always reverse the condition completely.^[4]

Antimicrobial agents, including metronidazole, amoxicillin/clavulanate potassium, ciprofloxacin, and rifaximin, can be used to treat bacterial overgrowth.

Achlorhydria resulting from long-term PPI use may be treated by dose reduction or withdrawal of the PPI.

Prognosis

Little is known on the prognosis of achlorhydria, although there have been reports of an increased risk of gastric cancer.^[5]

A 2007 review article noted that non-Helicobacter bacterial species can be cultured from achlorhydric (pH > 4.0) stomachs, whereas normal stomach pH only permits the growth of Helicobacter species. Bacterial overgrowth may cause false positive H. Pylori test results due to the change in pH from urease activity.^[6]

Small bowel bacterial overgrowth is a chronic condition. Retreatment may be necessary once every 1–6 months.^[7] Prudent use of antibacterials now calls for an antibacterial stewardship policy to manage antibiotic resistance.^[8]

Experiments have shown that non-Helicobacter bacteria can induce atrophic gastritis in achlorhydric mice, which in turn can cause gastric carcinoma.^[9]

References

^ Kohli, Divyanshoo R., Jennifer Lee, and Timothy R. Koch. "Achlorhydria." Medscape. Ed. B S. Anand. N.p., 29 Apr. 2015. Web. 25 May 2015.
^ El-Omar EM, Oien K, El-Nujumi A et al. (1997). "Helicobacter pylori infection and chronic gastric acid hyposecretion". Gastroenterology 113 (1): 15–24. doi:10.1016/S0016-5085(97)70075-1. PMID 9207257.
^ Divyanshoo Rai Kohli. "Achlorhydria Workup". Medscape. Retrieved 13 September 2014.
^ Iijima, K.; Sekine, H.; Koike, T.; Imatani, A.; Ohara, S.; Shimosegawa, T. (2004). "Long-term effect of Helicobacter pylori eradication on the reversibility of acid secretion in profound hypochlorhydria". Alimentary Pharmacology and Therapeutics 19 (11): 1181–1188. doi:10.1111/j.1365-2036.2004.01948.x. PMID 15153171. edit
^ Svendsen JH, Dahl C, Svendsen LB, Christiansen PM (1986). "Gastric cancer risk in achlorhydric patients. A long-term follow-up study". Scand. J. Gastroenterol. 21 (1): 16–20. doi:10.3109/00365528609034615. PMID 3952447.
^ Brandi G (Aug 2006). "Urease-positive bacteria other than Helicobacter pylori in human gastric juice and mucosa". Am J Gastroenterol. 101: 1756–61. doi:10.1111/j.1572-0241.2006.00698.x. PMID 16780553.
^ Divyanshoo Rai Kohli. "Achlorhydria Follow-up". Medscape. Retrieved 13 September 2014.
^ Lee CR, Cho IH, Jeong BC, Lee SH (Sep 12, 2013). "Strategies to minimize antibiotic resistance". Int J Environ Res Public Health. 10 (9): 4274–305. doi:10.3390/ijerph10094274. PMC 3799537. PMID 24036486.
^ Fox JG, Wang TC (2007). "Inflammation, atrophy, and gastric cancer.". J Clin Invest. 117 (1): 60–69. doi:10.1172/JCI30111. PMC 1716216. PMID 17200707.

UpToDate Contents

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English Journal

Effects of ezrin knockdown on the structure of gastric glandular epithelia.

Yoshida S1, Yamamoto H, Tetsui T, Kobayakawa Y, Hatano R, Mukaisho KI, Hattori T, Sugihara H, Asano S.
The journal of physiological sciences : JPS.J Physiol Sci.2015 Sep 2. [Epub ahead of print]
Ezrin, an adaptor protein that cross-links plasma membrane-associated proteins with the actin cytoskeleton, is concentrated on apical surfaces of epithelial cells, especially in microvilli of the small intestine and stomach. In the stomach, ezrin is predominantly expressed on the apical canalicular
PMID 26329936

Risk of community-acquired pneumonia in patients with a diagnosis of pernicious anemia: a population-based retrospective cohort study.

Almario CV1, Metz DC, Haynes K, Yang YX.
European journal of gastroenterology & hepatology.Eur J Gastroenterol Hepatol.2015 Jul 28. [Epub ahead of print]
OBJECTIVE: Pernicious anemia (PA) is an autoimmune disease that causes achlorhydria or profound hypochlorhydria. We conducted a population-based study to determine whether individuals with PA are at an increased risk for community-acquired pneumonia (CAP).METHODS: We performed a retrospective cohort
PMID 26225868

Is achlorhydria a cause of iron deficiency anemia?

Betesh AL1, Santa Ana CA1, Cole JA1, Fordtran JS2.
The American journal of clinical nutrition.Am J Clin Nutr.2015 Jul;102(1):9-19. doi: 10.3945/ajcn.114.097394. Epub 2015 May 20.
We re-evaluated the old hypothesis that gastritis-induced achlorhydria is a cause of iron deficiency anemia (IDA) in humans. First, we analyzed the currently available research on the association between achlorhydria and IDA. When gastric acid secretion was measured after maximal stimulation, the fr
PMID 25994564

Japanese Journal

Vasoactive intestinal polypeptide産生膵腫瘍による大量下痢からの循環・腎機能不全に対し持続的血液濾過透析など生命補助下に腫瘍切除しえた1例

廣瀬哲朗,西村充孝,東大介,高橋則尋,山岡竜也,安田勝太郎,石川順英,嶋田俊秀,荻野哲朗,西平友彦
日本消化器外科学会雑誌 43(6), 640-646, 2010-06-01
症例は60歳の女性で,1年前より腸炎症状にて輸液治療をされており,低カリウム,脚力低下にても入院歴あり.本年になり糖尿病指摘.交通事故を契機の精査で膵臓に10cm大の腫瘍を指摘された.治療目的で近隣病院に入院中1日あたり5〜8回におよぶ下痢による腎不全となり当院へ転送,循環不全,高度アシドーシス,低カリウムに対し輸液管理,塩酸ロペラミド・酢酸オクトレオチド投与,透析・持続的血液濾過透析で生命維持を …
NAID 110007656696

Unusual Multiple Gastric Carcinoids with Hypergastrinemia : Report of a Case

NAKATA KOHEI,AISHIMA SHINICHI,ISHIMIYA HITOSHI,YAO TAKASHI,MATSUURA TAKASHI,SEO MITSURU,NAGAI EISHI,OKIDO MASAYUKI,KATO MASATO,NAKAGAKI MITSURU,TSUNEYOSHI MASAZUMI,TANAKA MASAO
Surgery today : the Japanese journal of surgery 40(3), 267-271, 2010-03-01
NAID 10027394684

Intestinal Metaplasia : The Effect of Acid on the Gastric Mucosa and Gastric Carcinogenesis

Watanabe Hiromitsu,ワタナベヒロミツ,渡邊敦光
Journal of Toxicologic Pathology 23(3), 115-123, 2010
… Recent studies have shown that Cdx2 transgenic mice with gastric achlorhydria develop intestinal metaplasia and that in men and animals, Helicobacter pylori (H. …
NAID 130000450737

Related Pictures

★リンクテーブル★

リンク元	「水様下痢低カリウム血症無胃酸症候群」「無塩酸症」「無酸症」「gastric anacidity」「胃酸欠乏」
拡張検索	「watery diarrhea hypokalemia-achlorhydria syndrome」「watery diarrhea hypokalemic achlorhydria syndrome」「watery diarrhea, hypokalemia and achlorhydria症候群」「watery diarrhea-hypokalemia-achlorhydria syndrome」

「水様下痢低カリウム血症無胃酸症候群」

Achlorhydria
	Hydrogen chloride (major component of gastric acid)
Classification and external resources
ICD-10	K31.8
ICD-9	536.0
DiseasesDB	29513
eMedicine	med/18
MeSH	D000126