Gastric function test

Dr. Achla jain
Guest lecturer
SOS in Life sciences
Pt. Ravishankar shukla University, Raipur

The chief constituents of gastric juice are:
• HCl secreted by the parietal cells,
• Pepsinogen: Secreted by zymogen cells or
“chief” cells.
• Rennin: Not found in adult gastric juice.
Only found in infants/babies.
• Intrinsic factor: Required for
absorption of vitamin B12, and other
cells produce an alkaline mucus.

 The gastric mucosa has different
types of cell mucous secreting
surface epithelial cell oxyntic or
parietal cells chief or peptic cell.
 Daily volume of gastric secretion
is about 2000ml

To diagnose Gastric Ulcers
To exclude the diagnosis of Pernicious anaemia &
Peptic ulcer
For presumptive diagnosis of Zollinger Ellison
Syndrome
To determine the completeness of Surgical Vagotomy.

Gastric Residuum
1.Analysis of
Resting contents
Fractional gastric analysis using a test ‘meal’
2.Fractional Test
Meal Analysis
Stimulation by Alcohol or Caffeine or Histamine
or Insulin or Pentagastrin
3.Analysis after
Stimulation
Used as screening test
4.Tubeless
Gastric Analysis

Tests commonly employed for assessing gastric function are:
A. Examination of resting contents in resting juice (gastric residuum).
B. Fractional gastric analysis using a test ‘meal’.
C. Examination of the contents after stimulation:
 “Alcohol” stimulation.
 Caffeine stimulation.
 Histamine stimulation.
 Augmented histamine test.
 Insulin stimulation.
 Pentagastrin test.
D. Tubless gastric analysis.

Collection of Contents of Stomach
1. The stomach contents are collected after introducing a stomach
tube by nasogastric route into the stomach and removing the contents
by aspiration. The resting gastric contents are completely removed for
examination.
2. Gastric contents are removed after a “test meal” to see the
response of stomach. In this, small samples 5 to 6 ml of the gastric
contents are removed after every 15 minutes and the samples are
collected in small sterile clean penicillin bottles.

NORMAL ABNORMAL CAUSES
Volume
20-50mL
>100-120mL • Hypersecretion of Gastric juice
• Retention due to delayed
emptying
• Regurgitation of duodenal
contents
Consistency - Fluid Food residues • Carcinoma of stomach
Colour – clear-
colourless or slightly
yellowish or green
Dark red or
brown
Due to blood
• Bleeding Gastric ulcer
• Carcinoma of stomach
Bile – occasionally Increased
amount
• Intestinal Obstruction and ileal
stasis.
Mucus - small
amount
Increased
amount
• Gastritis and carcinoma of
stomach

NORMAL ABNORMAL CAUSES
Organic acid Lactic acid , butyric
acid present in large
amount
• Hypochlorhydria,
achlorhydria and Ca
stomach
Free acidity-measures
only HCl. 0-30mEq/L
>50mEq/L • Hyperacidity
Total acidity – includes HCl and other organic acids. Normal 10-40mEq/L
Pepsin Decreased levels
Increased levels
• Atrophic gastritis,
Ca stomach
• Zollinger-Ellison
syndrome

Fasting condition gastric juice is
aspirated using Ryle’s tube.
Gastric juice secreted for one hour is
collected as–Basal Secretion

Fractional Gastric analysis: Also called Fractional Test Meal (FTM)
It consists of the following steps:
1.Introduction of Ryle’s tube in stomach of a fasting patient (overnight).
2. Removal of residual gastric contents and its analysis.
3. Ingestion of “test meal”
4. Removal of 5 to 6 ml of gastric contents after meal by aspiration using a
syringe and analysis of the samples.

Fractional test meal or FTM
 Fasting stomach content aspirated (Ryle’s tube).
 Stimulation: Two pieces toast and tea or Oat meal porridge.
 Gastric Juice is collected in intervals.
 Total and Free Acidity of each are measured.
 Free acid more than 50 mmol/L: Duodenal/gastric ulcer, ZES.
Pyloric stenosis, Cholecystitis

 Collection of samples: At intervals of exactly 15 minutes, about
10 ml of gastric contents are removed by means of syringe
attached to the tube.
 Analysis of the samples: Each sample is strained through a fine
mesh cheese cloth. The residue on the cloth is examined for
mucus, bile, blood and starch. The strained samples are analyzed
for free and total acidity.

Results and Interpretation of the Tests
A. Normal Response
In normal health: After taking the meal, free acid is again found after
15 to 45 minutes. The free acid then rises steadily to reach a maximum
at about 15 mts to ½ hour, after which the concentration of free acid
begins to decrease. Free acid ranges from 15 to 45 mEq/ litre at the
maximum with total acid at about 10 units higher. About 80 per cent of
normal people fall within these limits. Blood should not be present and
there should not be any appreciable amount of bile.

B. Abnormal Responses
Three types of abnormal responses:
1. Hyperacidity (hyperchlorhydria): In which free acid reaches a
higher concentration than in normal persons.
2. Hypoacidity (hypochlorhydria): In which though free acid is
present, it is present in a concentration below the normal range.
3. Achlorhydria: In which there is no secretion of free acid at all.

Hyperchlorhydria
• Free acid
>50mEq/L
• Duodenal ulcer
• Gastric ulcer
• Gastric cell
hyperplasia
• Zollinger Ellison
Syndrome
Hypochlorhydria
• Ca of stomach
• Atonic
dyspepsia
Achlorhydria
• No HCl but
pepsin is
present
• Seen in Ca
stomach,
chronic gastritis
Achylia gastrica
• Both HCl and
pepsin are
absent
• Later stage of
Ca stomach
• Chronic gastritis
• Pernicious
anaemia

A. Alcohol Stimulation
 7% ethanol in 100ml
 Overnight fast, residual contents removed
 Sample every 15 min for 1 hour
 Check Total and Free acidity
 Pros: Rapid, Fast emptying, easy to administer than oat meal
 Cons: Non-physiological, more free acid.

B. Caffeine Stimulation
Caffeine can be used as a stimulus instead of alcohol.
Procedure
1. Ryle’s tube is introduced after an overnight’s fast and the resting
gastric contents are removed and analyzed.
2. Caffeine sodium benzoate, 500 mg dissolved in 200 ml of water is
given to the patient orally.
3. Samples of stomach contents are removed every 15 minutes and
analyzed for free and total acidity, peptic activity, blood, bile and
mucus. Advantages of caffeine stimulation is similar to alcohol
stimulation.

C. Histamine Stimulation Test
Histamine is a powerful stimulant for the secretion of HCl in the
normal stomach. It acts on receptors on the oxyntic cells,
increasing the cyclic AMP level, which causes secretion of an
increased volume of highly acidic gastric juice with low pepsin
content.

1. After an overnight’s fast, Ryle’s tube is passed into the stomach and
stomach contents are removed for analysis.
2. Patient is given a subcutaneous injection of histamine, 0.01 mg/kg body
wt.
3. After the injection, 10 ml of stomach contents are removed every 10
minutes for one hour. The samples are analyzed for free and total acidity,
peptic activity, and for presence of blood, bile and mucus.
Types of histamine test:
I. Standard histamine test and
II. Augmented histamine test.

Clinical significance
• Absence of free HCl in the secretions after histamine indicate “achylia
gastrica” (“true” achlorhydria).
• In duodenal ulcer: More juice may be secreted and a higher concentration
of acid may be found in the specimen obtained after histamine
administration than in normal cases.
I. Standard Histamine Test

II. Augmented Histamine Test (Kay)
 Histamine is a potent stimulus of gastric secretion .
 In this test 0.4mg/kg of histamine is given s.c, followed by
collection of gastric content
Disadvantage: Larger doses of histamine used in this test causes
untoward severe reactions and hence an antihistaminic will have
to be given side by side to prevent any such reactions.

• In normal persons: Up to 10 mEq/hour acid is present in the
prehistamine specimen, with 10 to 25 mEq in the combined post-
histamine ones.
• In pernicious anemia: No free HCl is secreted after augmented
histamine stimulation (achylia gastrica), but in other forms of
achlorhydria (false achlorhydria), some amount of free HCl is
secreted after histamine stimulation.
• In duodenal ulcers: Higher values are obtained sometimes
reaching even exceeding 100 mEq.

D. Insulin Stimulation Test (Hollander’s Test)
 Insulin stimulates HCl acid secretion
 0.1 -0.2 units/ kg body weight of soluble insulin IV
 Hypoglycemia occur in 30 minutes
 Vagatomy: No rise in acidity over BAO (basal acid output) is noticed
during hypoglycemia

Procedure
1. After an overnight fast, pass a Ryle’s tube and empty the stomach.
2. Then give 15 units of soluble Insulin intravenously(IV).
3. After injecting the insulin, withdraw approximately 10 ml samples of
gastric contents every 15 minutes for 2½ hours.
4. Samples to be analyzed for free and total acidity, peptic activity and
presence of blood, bile and starch. No starch should be present.

• In patients suffering from duodenal ulcer, before operation, there is a
marked and prolonged output of acid in response to insulin. The
concentration of free acid may rise well over 100 mEq/litre.
• After a successful vagotomy there is no response to Insulin and the
gastric acidity remains at a low level of 15 to 20 mEq/L, before and
after insulin injection.

E. Pentagastrin stimulation test
 The gastric secretion is stimulated by Pentagastrin.
 A synthetic penta-peptide with terminal 4 AA same as gastrin
 Dose: 6mg/kg body weight
 Gastric secretion: collected for 1 hour in 15 minutes interval.
 Volume and pH of the samples are measured.

• Normal basal secretion rate is 1 to 2.5 mEq/hour. After pentagastrin
stimulus, maximal secretion in normal persons roughly varies from 20
to 40 mEq/hr.
• In duodenal ulcer: The range was 15 to 83 mEq/hour with a mean of
43. Values above 40 mEq/hour has been kept which is suggestive of
duodenal ulcer.
• Zollinger-Ellison syndrome: It is characterised by a high basal
secretion usually above 10 mEq/hr; if, it is maximal then, there will be
no further rise after giving pentagastrin, otherwise only a small to
moderate increase is seen.
• In gastric ulcer: The test is of little value.

Serum pepsinogen
Pepsinogen determination has been used to investigate the gastric
secretion of this enzyme. A convenient method using the digestion
of dried serum has been used.
Interpretations
• Normal value: Ranges from 30 to 160 units/ml.
• Pernicious anaemia: Serum pepsinogen is absent or very low.
• Duodenal ulcer: An increase is often found upto and above twice
the upper limit of normal. If the serum pepsinogen is less than <
80 units/ml; it is considered that an ulcer is not present.

 Fasting secretion is stimulated by histamine analogue (3-
β amino ethyl pyrazole or “Histalog”) 10-50mg.
 Dye coupled resin (“Azure-A”) is given orally
 Based on the pH of the surrounding, resin release the dye
 The dye is excreted through urine, and the quantity excreted
provides indication of presence or absence of HCl

Gastric function test

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