This document summarizes various gastric function tests used to evaluate acid secretion in the stomach. It describes: 1. The anatomy and functions of the stomach, including acid secretion by parietal cells. 2. Indications for gastric function tests such as diagnosing ulcers, pernicious anemia, or post-surgery evaluation. 3. Types of tests including analysis of fasting gastric contents, fractional or stimulated tests using substances like alcohol, caffeine, or histamine to measure acid levels.

1. GASTRIC FUNCTION TESTS
Dr.Rittu Chandel
M.D. Biochemistry (second yr)
Grant Govt. Medical College
Mumbai -400008
24-09-13

2. anatomy

3. functions
1. Reservoir of ingested foodstuffs
2. Mixing of food with gastric secretion until it
forms a semifluid mixture called chyme
3. Secretes substances which are responsible for
initiation of digestion

4. Oxyntic gland

5. Secretion of gastric HCl
•
•
•
•
Parietal cells ----------HCl
pH in gastric lumen ------- 0.8
(very low as compared to blood pH ---- 7.4)
Hence protons are transported against
concentration gradient by active process

7. Indications of gastric function tests
1. Diagnosis of gastric ulcer
2. Exclusion of diagnosis in pernicious anemia
3. Presumptive diagnosis of Zollinger – Ellison
syndrome
4. Determination of completeness of surgical
vagotomy

8. classification
1.Examination of resting contents in resting juice
2.Fractional test meal
3.Examination of contents after stimulation
alcohol stimulation
caffeine stimulation
histamine stimulation
augmented histamine test
insulin stimulation test
pentagastrin test
4.Tubeless gastric analysis

9. Collection of sample
• Collection of contents of stomach
After overnight fast
After test meal
• Types of stomach tubes
Rehfuss tube
Ryles tube
• Markings on tube
Single ring reaches lips
Tip reaches cardiac end
Double ring reaches lips
Tube in body of stomach

10. Examination of resting contents
1.Volume
Normal ----20 – 50 ml
Abnormal -----greater than 100 – 120 ml
Hypersecretion of gastric juice
Retention of gastric contents due to delayed emptying
Due to regurgitation of duodenal contents
2.Consistency
Normal -----fluid
Abnormal ----food residues

11. 3.Colour
Normal -----clear or colourless
Abnormal ------bright red/dark red/brown colour
4.Bile
5.Blood
6.Free and total acidity
Determined by titrating a portion of the filtered
specimen with standard solution of NaOH

12. Two indicators are used in succesion
indicators
Measures pH
Methyl orange
2.9 to 4.4 (red ------yellow)
phenolphthalein
8.3 to 10
inferences
(yellow ----- red )
Free acidity
First titration
0 – 30 mEq/L
Total acidity
Complete titration
10 – 40 mEq/L
Combined acid
Difference between two
titrations

13. 7. Mucus
8.Organic acids
Absence of HCl ------micro organisms thrive and
ferment food residues to produce organic acids,
lactic acid and butyric acid

14. Fractional gastric analysis/fractional
test meal
Introduction of ryles tube in stomach of fasting patient
Removal of residual gastric contents and its analysis
Ingestion of test meal
Analysis of samples

15. interpretation

16. Abnormal responses
Hyperacidity/hyperchlo Max free acidity exceeds Duodenal ulcer
rhydria
45 mEq/L
Gastric ulcer
Gastric carcinoma
hyperirritability
hypoacidity
Free acid below the normal
range
Pernicious anemia
achlorhydria
No secretion of HCl but
enzyme pepsin is present
Carcinoma stomach
Partial gastrectomy
Pernicious anemia
Hyperthyroidism
myxedema
Achylia gastrica – both enzymes and acids are absent indicating complete absence of
gastric secretions
Advanced gastric cancer
Typically seen in pernicious anemia and subacute combined degeneration of spinal

17. Stimulation tests – alcohol stimulation
test
Overnight fast, ryles tube passed –
• Alcohol stimulation test
resting contents removed for
analysis
100 ml of 7% ethyl alcohol is
administered
Samples removed after every 15
mins and analysed for free and
total acidity, presence of
bile, blood and mucus

18. • Caffeine stimulation
Stimulus ----caffeine sodium benzoate (500 mg in
200 ml water) given orally
• Histamine stimulation test
Powerful stimulant for HCl in normal stomach
Acts on receptors of oxyntic cells, increasing cAMP,
which causes secretion of increased volume of high
acidic gastric juice with low pepsin content
Best to differentiate between true achlorhydria from
false achlohydria

19. • Augmented histamine test
Normal persons
Upto 10 mEq/hr acid is
present in pre histamine
specimen , with 10 -25
mEq in post histamine
specimens
Pernicious anemia
No free HCl secreted
Duodenal ulcer
> 100 meq
Now histalog ( 3β –aminoethylpyrazole) is used in place of histamine

20. Insulin stimulation test (hollander’s
test)
• Potent stimulus for gastric acid secretion –
hypoglycemia
• Indication
To check the effectiveness of vagotomy in patients
with duodenal ulcer
Stimulus – 15 unit of soluble insulin iv

22. Pentagastrin test
• Synthetic peptide
• N terminal ----butyloxycarbonyl –β alanine
• C terminal ---- Trp – Met – Asp – Phe
• Measure of total parietal mass
• Stimulus – 6 micg/kg body wt given sc

23. condition
Basal secretion
Maximal scretion
normal
1 – 2.5 mEq/hr
20 – 40 mEq/hr
Duodenal ulcer
Above 40 mEq/hr
Gastric cancer
True achlorhydria
Pernicious anemia
True achlorhydria

24. Tubeless gastric analysis
• Quininium resin given orally
• in stomach quinine ions liberted at pH < 3
• Quinine liberated forms quinine HCl which is
excreted in urine
• Quinine is extracted and determined
fluorimetrically
• Thus it gives indirect measure for acid secretion

25. • Only a screening test
• Positive result – acid being secreted
• Negative result - unreliable indicator of true
achlorhydria
• Test not reliable in patients suffering from renal
diseases, urinary retention, malabsorption

26. biblography
• Guyton
• Satyanaryan
• Ranna shinde
• THANK YOU