Gastric Acid Secretion Test (Gastric Acid Stimulation Test)

Norm of Gastric Acid Secretion Test (Gastric Acid Stimulation Test)

Within normal limits.

Basal (Prestimulation) Acid Output (BAO) Is the Gastric Acid Secreted Without Stimulation		SI Units
Adult Female
Normal	1–4 mEq/hour	1–4 mmol/hour
Duodenal ulcer	3–8 mEq/hour	3–8 mmol/hour
Gastric carcinoma	0–3 mEq/hour	0–3 mmol/hour
Gastric ulcer	1–3 mEq/hour	1–3 mmol/hour
Atrophic gastritis	0 mEq/hour	0 mmol/hour
Pernicious anemia	0 mEq/hour	0 mmol/hour
Zollinger-Ellison syndrome	>20 mEq/hour	>20 mmol/hour
Adult Male
Normal	2–5 mEq/hour	2–5 mmol/hour
Duodenal ulcer	5–10 mEq/hour	5–10 mmol/hour
Gastric carcinoma	0–3 mEq/hour	0–3 mmol/hour
Gastric ulcer	1–5 mEq/hour	1–5 mmol/hour
Atrophic gastritis	0 mEq/hour	0 mmol/hour
Pernicious anemia	0 mEq/hour	0 mmol/hour
Zollinger-Ellison syndrome	>20 mEq/hour	>20 mmol/hour

 

Maximum (Stimulated) Acid Output (MAO) Is the Gastric Acid Output After Stimulation (Sum of Four 15-Minute Specimens)
Adult Female
Normal	7–15 mEq/hour	7–15 mmol/hour
Duodenal ulcer	10–20 mEq/hour	10–20 mmol/hour
Gastric carcinoma	0–5 mEq/hour	0–5 mmol/hour
Gastric ulcer	5–15 mEq/hour	5–15 mmol/hour
Atrophic gastritis	0 mEq/hour	0 mmol/hour
Pernicious anemia	0 mEq/hour	0 mmol/hour
Zollinger-Ellison syndrome	35–60 mEq/hour	35–60 mmol/hour
Adult Male
Normal	5–26 mEq/hour	5–26 mmol/hour
Duodenal ulcer	15–35 mEq/hour	15–35 mmol/hour
Gastric carcinoma	0–20 mEq/hour	0–20 mmol/hour
Gastric ulcer	10–20 mEq/hour	10–20 mmol/hour
Atrophic gastritis	0 mEq/hour	0 mmol/hour
Pernicious anemia	0 mEq/hour	0 mmol/hour
Zollinger-Ellison syndrome	35–60 mEq/hour	35–60 mmol/hour
BAO:MAO Ratio
Normal	1:2.5–1:5	0.3–0.6
Gastric ulcer/gastric carcinoma		20%
Gastric ulcer/duodenal ulcer		20%–40%
Duodenal ulcer/Zollinger-Ellison syndrome		40%–60%
Zollinger-Ellison syndrome		>60%

 

Peak Acid Output (PAO) Is 2 × Total Values of the Two Highest 15-Minute MAO Samples; BAO:PAO Ratio	SI Units
Adult Female	0.23
Adult Male	0.29

 

Usage of Gastric Acid Secretion Test (Gastric Acid Stimulation Test)

Diagnosis and evaluation of duodenal ulcer, gastric carcinoma, gastric ulcer, pernicious anemia, postoperative stomal ulcer, and Zollinger-Ellison syndrome.
Increased of Gastric Acid Secretion Test (Gastric Acid Stimulation Test)
Duodenal ulcer, gastric ulcers in some cases, peptic ulcer disease, pyloric ulcer, and Zollinger-Ellison syndrome. Drugs include adrenergic blockers, alseroxylon, caffeine, calcium salts, cholinergics, corticosteroids, deserpidine, ethyl alcohol (ethanol), rescinnamine, and reserpine.
Decreased of Gastric Acid Secretion Test (Gastric Acid Stimulation Test)
Achlorhydria, anemia (pernicious), Crohn's disease, gastric atrophy, gastric neoplasm, gastric ulcer, and gastritis. Nasojejunal feeding tubes in mechanically ventilated clients. Drugs include antacids, anticholinergics, beta-blocking agents, cimetidine, famotidine, nizatidine, ranitidine hydrochloride, and tricyclic antidepressants.

 

Description of Gastric Acid Secretion Test (Gastric Acid Stimulation Test)

Gastric acid is secreted by the parietal cells of the stomach in response to neurologic and hormonal stimulation. Gastric acid is secreted during the gastric phase of digestion and aids in the breakdown of proteins and in the absorption of vitamin B12, folic acid, and iron. It consists of hydrochloric acid (HCl), electrolytes, enzymes, and mucus. It is colorless and very acidic, with a pH of <2.5. In the presence of tumors, ulcerative disease, or pernicious anemia, the rate of gastric acid secretion by the parietal cells can be altered. A diagnostic gastric acid stimulation test involves aspirating and collecting basal and maximal acid outputs. Histalog (betazole, a histamine analog) or histamine diphosphate is injected intramuscularly to stimulate gastric acid secretion. By measurement of the rate and volume of gastric acid, gastric function can be evaluated.

 

Professional Considerations of Gastric Acid Secretion Test (Gastric Acid Stimulation Test)

Consent form NOT required.

Risks
Allergic reaction to injection (itching, hives, rash, tight feeling in the throat, shortness of breath, bronchospasm, anaphylaxis, death).
Contraindications
Positive skin test. Use of histamine diphosphate is contraindicated for clients who have a history of asthma, paroxysmal hypertension, urticaria, or other allergic conditions. Histalog (betazole hydrochloride) has a lower incidence of side effects than histamine diphosphate.

 

Preparation

1. Perform a skin test to determine hypersensitivity by injecting 0.1 mL of Histalog or histamine diphosphate subcutaneously. Wait 30 minutes for a reaction to occur. If the wheal exceeds 10 mm in diameter, do not perform the stimulation portion of this test.
2. Obtain a Levin tube, lubricant, 8–12 clean plastic containers without preservative, a Toomey syringe, suction equipment, a marker or grease pencil, and histamine diphosphate or Histalog.
3. Prepare suction apparatus and tubing.
4. See Client and Family Teaching.

 

Procedure

1. Position the client sitting or lying on the left side.
2. Insert a Levin tube with a radiopaque tip through the client's nose or mouth into the stomach. Position the tube tip in the lumen below the stomach fundus and confirm the placement by radiography or fluoroscopy.
3. Reposition the client to a sitting position and wait at least 10 minutes before proceeding further.
4. Apply low continuous suction to the Levin tube. At 15 and 30 minutes, withdraw two specimens with a Toomey syringe and discard the aspirate.
5. Begin continuous aspiration of the gastric contents, using the syringe, for a total of 60 minutes. Collect the aspirate into the collection containers (labeled 1, 2, 3, 4), using a new collection container every 15 minutes until basal acid output collection is complete.
6. Administer Histalog (betazole hydrochloride) 0.5 mg/kg of body weight, or histamine diphosphate 0.1 mg/kg of body weight, intramuscularly, and begin post-stimulation collections, as in the preceding step, immediately. Observe for hypersensitivity reaction.
7. Poststimulation collection should continue for 1 hour (four specimens) if histamine diphosphate was used, or for 2 hours (eight specimens) if Histalog was used.

 

Postprocedure Care

1. Send all 8–12 containers, identified as basal or post stimulation, to the laboratory.
2. Remove the Levin tube.
3. Resume previous diet.
4. Observe for nausea and vomiting.

 

Client and Family Teaching

1. Fast from food for 12 hours and from water for 1 hour before the procedure.
2. Do not smoke or chew gum, and avoid stressful situations for 4 hours before the test.
3. The test involves the insertion of a tube through the nose into the stomach and periodic removal of the stomach contents with a syringe through the tube. The test may cause symptoms of indigestion because a drug that stimulates gastric acid secretion is given. Mild, temporary discomfort may be experienced during tube insertion. Lidocaine jelly may be used as lubricant to decrease discomfort of tube insertion.
4. The test takes more than 2 hours.
5. Results are normally available within 24 hours.

 

Factors That Affect Results

1. Histamine antagonists or anticholinergics and antacids should be discontinued 72 and 12 hours, respectively, before the test. If, however, the objective is to test the effectiveness of a histamine antagonist on acid secretions, the drugs should be continued, and the basal output of gastric acid should be performed 1 hour after administration of a morning dose.
2. Stimuli that may increase gastric acid production include smoking, the sight or odor of food, or stimuli that cause the client to become angry, fearful, or depressed.
3. Peak acid output after Histalog may not occur until the second hour after administration.

 

Other Data

1. None.