Medical Term for Gastric Acidity
The medical term for gastric acidity is gastric acid secretion or gastric acid hypersecretion when referring to excessive production, with the physiologic process involving hydrochloric acid (HCl) production by parietal cells in the stomach 1.
Core Terminology and Physiologic Context
Gastric acid secretion refers to the production of hydrochloric acid by specialized parietal cells in the stomach, achieving a pH close to 1, which represents more than a one million-fold increase in H+ ion concentration compared to blood and intracellular medium at pH 7.4 1. This process is mediated by the H+/K+ ATPase enzyme system (the proton pump) at the secretory surface of gastric parietal cells 2.
Related Clinical Terms
Hypersecretion or gastric acid hypersecretion describes pathologically elevated acid production, defined as basal acid output greater than 10 mmol/h in the absence of elevated fasting serum gastrin 3
Hypochlorhydria refers to reduced gastric acid production, while achlorhydria indicates complete absence of acid secretion 4
Rebound acid hypersecretion (RAHS) describes the physiologic phenomenon of increased acid production following discontinuation of prolonged proton pump inhibitor therapy 5
Measurement and Clinical Assessment
Basal acid output is the standard quantitative measure, with normal values typically less than 10 mmol/h 3. Intragastric pH monitoring provides direct assessment, with gastric fluid pH of 1 to 2 considered normal and protective against ingested pathogens 6. The 24-hour esophageal pH monitoring test is the most sensitive and specific method for linking acid reflux to clinical symptoms 5.
Key Physiologic Parameters
Gastric acidity maintains a pH of approximately 1-2 in the fasting state, which facilitates protein digestion, iron and calcium absorption, vitamin B12 absorption, and protection against bacterial overgrowth 7
The antisecretory effect of proton pump inhibitors can achieve 78-94% decrease in basal acid output and 79-88% decrease in peak acid output with standard dosing 2
Normal elderly adults maintain basal unstimulated gastric acidity (pH <3.5) in approximately 84% of cases, contrary to older assumptions about age-related achlorhydria 4
Clinical Relevance and Pathophysiology
When homeostatic mechanisms malfunction, excessive acid volume and concentration may overwhelm mucosal defense mechanisms, leading to duodenal ulcer, gastric ulcer, and gastroesophageal reflux disease 7. The main peripheral stimulants of acid secretion are the hormone gastrin and the paracrine amine histamine, while somatostatin acts as the main inhibitor 7.
Important Clinical Distinctions
The term "acid reflux disease" should be replaced by the more general term "reflux disease" unless definitively shown to apply, as not all gastroesophageal reflux disease involves acid reflux 5
Hypersecretory states such as Zollinger-Ellison syndrome represent pathologic conditions requiring lifelong acid suppression and should never undergo proton pump inhibitor de-prescribing 5
Gastric acid secretion increases with repeated once-daily proton pump inhibitor dosing, reaching a plateau after four days, with serum gastrin levels rising during the first 1-2 weeks of therapy 2