hypochlorhydria

低酸症、低塩酸症

関

achlorhydria

WordNet

1. 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）』「2015/06/22 13:31:27」(JST)

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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

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. 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.
• 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).

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.

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.

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.

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

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

See also

• Hyperchlorhydria
• Atrophic gastritis
• Isopropamide
• Fundic gland polyposis

References

UpToDate Contents

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• 1. 胃酸分泌の生理学 physiology of gastric acid secretion
• 2. 化生（慢性）萎縮性胃炎 metaplastic chronic atrophic gastritis
• 3. VIP産生腫瘍症候群 the vipoma syndrome
• 4. 小腸内細菌過剰繁殖の病因および発症機序 etiology and pathogenesis of small intestinal bacterial overgrowth
• 5. ヘリコバクターピロリ菌感染と消化管悪性腫瘍の関連性 association between helicobacter pylori infection and gastrointestinal malignancy

English Journal

• Review article: the investigation and management of gastric neuroendocrine tumours.

• Basuroy R1, Srirajaskanthan R, Prachalias A, Quaglia A, Ramage JK.
• Alimentary pharmacology & therapeutics.Aliment Pharmacol Ther.2014 May;39(10):1071-84. doi: 10.1111/apt.12698. Epub 2014 Mar 13.
• BACKGROUND: Gastric carcinoids (GCs) or neuroendocrine tumours (NETs) are increasingly identified at endoscopy, and account for 0.6-2% of all gastric polyps identified. The SEER database in the US has demonstrated a rising incidence of gastric NETs amongst all NETs; from 2.2% between 1950 and 1969 t
• PMID 24628514

• Histogenesis and Natural History of Gut Neuroendocrine Tumors: Present Status.

• Solcia E1, Vanoli A.
• Endocrine pathology.Endocr Pathol.2014 Apr 4. [Epub ahead of print]
• Important progress has been made during the last decade in the histopathologic characterization and overall prognostic evaluation of gut neuroendocrine tumors. However, some issues like tumor histogenesis, typing, functional characterization, and preferred site of origin deserve further clarificatio
• PMID 24699926

• Helicobacter pylori-induced posttranscriptional regulation of H-K-ATPase α-subunit gene expression by miRNA.

• Zhang YM1, Noto JM, Hammond CE, Barth JL, Argraves WS, Backert S, Peek RM Jr, Smolka AJ.
• American journal of physiology. Gastrointestinal and liver physiology.Am J Physiol Gastrointest Liver Physiol.2014 Apr 1;306(7):G606-13. doi: 10.1152/ajpgi.00333.2013. Epub 2014 Feb 6.
• Acute Helicobacter pylori infection of gastric epithelial cells induces CagA oncoprotein- and peptidoglycan (SLT)-dependent mobilization of NF-κB p50 homodimers that bind to H-K-ATPase α-subunit (HKα) promoter and repress HKα gene transcription. This process may facilitate gastric H. pylori colo
• PMID 24503769

Japanese Journal

• Cutoff Serum Pepsinogen Values for Predicting Gastric Acid Secretion Status

• Iijima Katsunori,Koike Tomoyuki,Abe Yasuhiko,Shimosegawa Tooru
• The Tohoku Journal of Experimental Medicine 232(4), 293-300, 2014
• … After checking the correlation between gastric acid secretion and serum pepsinogen, the receiver operating characteristics analyses were employed for determining the most suitable cutoff points of serum pepsinogen for the gastric acid secretion status (i.e., hypochlorhydria, profound hypochlorhydria, and hyperchlorhydria). …
• NAID 130004460122

• Gastric hypochlorhydria is associated with an exacerbation of dyspeptic symptoms in female patients

• IWAI Wataru,ABE Yasuhiko,IIJIMA Katsunori,KOIKE Tomoyuki,UNO Kaname,ASANO Naoki,IMATANI Akira,SHIMOSEGAWA Tooru
• Journal of gastroenterology 48(2), 214-221, 2013-02-01
• NAID 10031156307

• 皺襞肥大型胃炎の診断と治療

• 村山 洋子,佐野村 珠奈,篠村 恭久,西林 宏之,安永 祐一,筒井 秀作
• 日本消化器内視鏡学会雑誌 55(2), 237-249, 2013
• 胃体部の皺襞肥大は，内視鏡検査や胃X線検査時にしばしば観察される．その大多数は<I>Helicobacter pylori</I>（<I>H. pylori</I>）感染により惹起される皺襞肥大型胃炎である．その特徴は，胃体部粘膜の腺窩上皮の過形成および高度の炎症を認め，胃酸分泌の低下を伴い，皺襞肥大の程度に従って胃癌のリスクが増加し，特に胃体部に未 …
• NAID 130003375248

Related Links

• Hypochlorhydria | Define Hypochlorhydria at Dictionary.com

hypochlorhydria hy·po·chlor·hy·dri·a (hī'pō-klôr-hī'drē-ə) n. An abnormally low level of hydrochloric acid in the stomach.

• hypochlorhydria - definition of hypochlorhydria by Medical ...

hypochlorhydria /hy·po·chlor·hy·dria/ (-klor-hi´dre-ah) lack of hydrochloric acid in the gastric juice. hy·po·chlor·hy·dri·a (hī′pō-klôr-hī′drē-ə) n. An abnormally low level of hydrochloric acid in the stomach. hypochlorhydria [-klôrhid′rē·ə] ...

Related Pictures

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★リンクテーブル★

リンク元	「プロトンポンプ阻害薬」「低酸症」「低塩酸症」

「プロトンポンプ阻害薬」

　　[★]

英

proton pump inhibitor PPI

同

プロトン-カリウムATPアーゼ阻害薬 proton-potassium ATPase inhibitor、H＋ポンプ阻害薬

• 命名法："-azole"
• 特徴

胃潰瘍の治癒率を向上する (⇔H2受容体拮抗薬)

プロトンポンプ阻害薬

• 消化性潰瘍治療薬

• 攻撃因子抑制剤

• プロトンポンプ阻害薬

• オメプラゾール omeprazole
• ランソプラゾール lansoprazole
• ラベプラゾール rabeprazole

相互作用

　プロトンポンプ　
　　H+/K+ ATPase　・・・これはNa+/K+ ATPaseと60%相同性を持つ
　　　2,4のαサブユニットと同数のβサブユニットを含む。
　　　　αサブユニット10回膜貫通, 120-150kDa, glycoprotein
　　　　αは管腔側、原形質膜まで。細胞内輸送に必要。
　　　　βサブユニットは管腔側に突き出ており、反対側は膜内に埋もれている。

　休止期には小胞体内内腔へのH+,K+,Cl-の移動、分泌期には小胞は管腔の細胞膜と癒合してK+, Cl-を管腔側に排出する一方でH+を排出でしてK+を取り込む。

　PPIは弱塩基性

　PPIはH+と反応してPPIaとなりS-S-活性体となり、H+,K+-ATPaseのSH基と結合して不可逆的に阻害する。

　比較
　　PPI：胃潰瘍の治癒率↑
　　H2R阻害薬：十二指腸潰瘍の治癒率↑

　PPI問題
　　胃潰瘍8
　　十二指腸6
　　逆流性食道炎8
　副作用
　　血中ガストリン↑→ECL cell↑→リバウンドが激しい
　　week end therapy: 週末3日だけ投与後休薬
　　ピレンゼピン(Mi R blocker), PG(プロスタグランジン)　→　ガストリン↑を軽減
　　ラベプラゾール：ガストリン濃度を上げず酸分泌↓
　　　→リバウンドが少ない。

　PPI抵抗性潰瘍：PPIによる酸分泌抑制不十分
　①個人差によるPPIの用量不足
　②胃内でのPPIの不活性化→
　　胃内容の排泄遅延。PPIが不活化、アルカリに晒される。

副作用

http://www.uptodate.com/contents/overview-and-comparison-of-the-proton-pump-inhibitors-for-the-treatment-of-acid-related-disorders?source=search_result&search=%EF%BC%B0%EF%BC%B0%EF%BC%A9&selectedTitle=1~150#H59974871

• 感染：

• クロストリジウム・ディフィシル感染症
• その他：リスクの大きさははっきりしていないが。カンピロバクター感染症、サルモネラ感染症
• 肺炎：上部消化管に細菌がcolonizeしやすくなるからだそうですが。

• 代謝

• 低マグネシウム血症：PPI使用で腸管吸収が低下するらしい。
• 骨粗鬆症：カルシウムの吸収障害。低Cl血症(hypochlorhydria)によりカルシウムの吸収が低下するらしい
• ビタミンB12欠乏症
• 鉄欠乏症

• 高ガストリン血症
• 無酸性胃炎
• 急性間質性腎炎(AIN)

「低酸症」

　　[★]

英

hypochlorhydria

関

低塩酸症

-hypochlorhydria

「低塩酸症」

　　[★]

英

hypochlorhydria

関

無酸症、低酸症