3. 3
Gastric function test:
Introduction:
The stomach is the major organ of digestion and performs the
following function.
Disease of stomach and duodenum alteration of gastric
secretion often occurs.
Chemical examination of Gastric juice and contents
importents for the diagnosis of some disease.
eg: Peptic ulcer, Cancer of Stomach.
To obtained a complete data of gastric function the contents
of the stomach is examined.
a) During the resting Period.
b) During the period of digestion after giving a meal.
c) After stimulation.
R.E.B, 4MedStudents.com, 2003
4. Secretion of Gastric Function
The function of this gastric secretion is two-fold:
A. to break down food into more absorbable components.
B. to aid in the destruction of most ingested bacteria.
The stomach can produce about 2.4 L per day of these gastric
secretions.
Gastric secretions also contain the enzyme pepsin, which is
important for initiating protein digestion.
4
5. Secrection of Gastric HCL:-
The Perital cell of Gastric gland produce HCL.
The pH in the gastric lumen is as low as 0.8
Fig: Mechanism of HCL Secretion
Lumen Parital cell Blood
Co2 + H20
Carbonic anhydrase
ATP H2Co3
K+ K+
H+ H+ HCo3- HCo3-
HCL ADP+ Pi
Cl- Cl- CL-
5
6. Chief constituents of gastric juice:
HCl
Pepsinogen
Rennin
Intrinsic Factor
Indication of gastric function test:
Diagnosis of gastric ulcer.
Exclusion of diagnosis of pernicious anaemia and peptic ulcer in
a patients with gastric ulceration.
Diagnosis of Zollinger- ellison Syndrome.
6
7. Collection of sample:
1) Preparation of Patients:
Early morning specimen is collected.
2) Collection:
Gastric juice is collected by 3 stomach tubes:
a) Ryle’s tubes
b) Refuss tubes
c) Levine tubes
3) Samples:
Fasting samples.
Post stimulation/ Fractional test meals.
7
8. Classification:
1) Examination of resting contents Gastric juice.
2) Fractional test Meal.
3) Examination of Contents after stimulation.
a) caffeine Stimulation.
b) Alcohol Stimulation.
c) Histamine Stimulation.
d) Augmented histamine test.
e) Insulin Stimulaton.
f) Pentagastrin test.
4) Tubeless Gastric analysis.
8
9. Examination of gastric contents:
Free and total acidity:
Indicator:
1)Methyl orange 0.1 % aqueous solution:
> Topfer’s indicator is also used for free acidity.
> measure pH 2.9 to 4.4.
> changes red to yellow.
2) Phenolphthalein 1%
> It is used for total acidity.
> measure 8.3 to 10
> changes yellow to red.
Inferences:
The following inferences should be obtained.
Free acidity:
The first titration to about pH- 4.0 measure the amount of free Hcl presents.
9
10. Total acidity:
The complete titration is said to give a total acidity.
Some protein Hydrochloride and any organic acids presents are
titrated.
Protein presents include mucin in the gastric secretion and
protein in meals are titrated.
Combined Acids:
The difference between these two titration gives combined
acids.
Normal range:
Free Acids = 0 to 40 meq/l
Total Acids = 10 to 50 meq/l 10
11. 2) Fractional test meals:
Sample collection:
Introduce the Ryles tube into the stomach of a
patients who is fasting for 12 hrs/overnight.
Removal of residual Gastric contents and it’s analysis.
Ingestion of test meals.
Removal of 10ml of gastric contents at 15 min
interval till for 2hrs.
11
12. Analysis of the Sample:
The residue on the Cloth is examine for:
a) mucus.
b) Bile
c) Blood
d) Starch
The Strained Sample are analysed for free and total acidity.
Normal Range:
a) Free acidity = 0-40mmol/l
c) Total acidity = 10- 50 mmol/l
12
13. Stimulation test:
1) Caffeine Stimulation:
Caffeine can be used as a
stimulus instead of Alcohol.
Procedure:
Ryle’s tube is introduced after an over night’s fast and the resting
gastric contents are removed and analysed.
Caffeine Sodium Benzoate 500mg dissolved in 200ml of water is given
to the patients orally.
Sample removed from stomach in every 15 min.
Analysed for free and total acidity, peptic activity, blood, bile and
mucus.
13
14. Advantage:
This test is more easily administered.
Specimen are clear and analysed easily.
The Stomach empities are more quickly.
3) Histamine Stimulation test:
Powerful Stimulant for the Secretion of HCL in Normal stomach.
histamine + receptor (oxyntic cell)
Increasing the cyclic AMP level
which cause
ed secretion of highly gastric juice with low pepsin content.
14
15. 4)Insulin Stimulation tests:
Done in patients who had undergone vagotomy as a treatment
of duodenal ulcer
Procedure:
Overnight fast Ryles tube is passed and empty the stomach.
Than give 15 units of soluble insulin intravenously
After injecting withdraw approxmately 10 ml sample of gastric
contents every 15 min for 2 1/2 hrs.
Sample to be analysed for free and total acidity, presence of
blood, bile.
15
16. Clinical significance:-
1) In duodenal ulcer:
> Marked and prolonged output of acid in response to insulin.
2) After sucessful Vagotomy:
> Ther is no response to insulin and the gastrc acidity remains at a low
level.
16
17. 6) Alcohol Stimulation:
Procedure:
Overnight fast Ryles tube is passed into the stomach
and the resting contents are removed and analysis.
100ml of 7% ethyl alcohol is administerd.
Sample of gastric contents are collected at an
interval of 15 min
and all the sample are analysed for free and total
acididty, Peptic activity,presence of bile, blood and
mucus. 17
18. Advantage:
More easily administered and prepare.
Consumed better.
The gastric response is more rapid and more intense.
Quick empyting of the stomach.
Specimen are clear and easily analysed.
Disadvantage:
Stimulous with alcohol is more vigrous.
Free acidity are higher and normal limits are wider.
18
19. Abnormality of Gastric function:
Increased Gastric HCl secretion is found in:
a) Zollinger- Ellison Syndrome.
b) Chronic duodenal ulcer.
c) gastric cell Hyperplasia.
d) Excessive Histamine production.
Decreased Gastric HCl secretion is found in:
a) Gastritis
b) Gastric Carcinoma.
c) Pernicious anaemia.
19
20. Imp term for gastric function test:
Hyperchlorhydria.
Hypochlorhydria.
Achlorhydria
Achlya gastrica.
20
