Download MBBS (Bachelor of Medicine and Bachelor of Surgery) Latest Gastric Function Tests I Lecture PPT
GASTRIC
FUNCTION TESTS
DR . SUDHANSHU SHEKHAR
ASSOCIATE PROFESSOR
DEPT. OF BIOCHEMISTRY
Indications of gastric function tests
1. Diagnosis of gastric ulcer
2. In chronic duodenal ulcer
3. Evaluate pernicious anemia in adult
4. Presumptive diagnosis of Zollinger ? Ellison
syndrome
5. Determination of completeness of surgical
vagotomy
CLASSIFICATION
1.Examination of resting contents in resting juice
(GASTRIC RESIDUM )
2.Fractional test meal
3.Examination of contents after stimulation
a) Alcohol stimulation
b) Caffeine stimulation
c) Histamine stimulation
d) Augmented histamine test
e) Insulin stimulation test
f) Pentagastrin test
4.Tubeless gastric analysis
5. Endoscopy
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
Examination of resting contents
1.Volume
Normal ----20 ? 50 ml
Abnormal -----greater than 100 ? 120 ml
Hypersecretion of gastric juice
I. Retention of gastric contents due to delayed
emptying
II. Due to regurgitation of duodenal contents
2. Consistency
Normal -----fluid
Abnormal ----food residues ( Ca stomach)
.
3.Colour
Normal -----clear or colourless
Abnormal ------
slightly yellow /green -- regurgitation of bile
red brown--- due to presence of blood
4.Bile
Intestinal obstruction
Ileal stasis
.
5.Blood
In trace amount ? may be due to trauma during
Ryles tube passage
Increased amount ?
Gastric carcinoma
Erosive gastritis
Bleeding peptic ulcer
6. Mucus
Normal --- small amount
Increased mucus ----gastritis and gastric
carcinoma
.
7. Organic acids
Absence of HCl ------micro organisms thrive and
ferment food residues to produce organic acids,
lactic acid and butyric acid
8. Pepsin
Absence ---Achylia Gastrica
Incresed --- Z E syndrome
duodenal ulcer
gastritis
Decresed --- chief cell mass
atrophic gastritis
gastric carcinoma
9. FREE AND TOTAL ACIDITY
Free acidity (0 ? 30 mEq/L)
measures only HCl
it is measured by titration with N/10 NaOH using
Topfer's reagent as indicator
Combined acidity ( FA-TA)
include Protein hydrochlorides, acid phosphates, and
organic acids like lactic acid and other organic acids
Total Acidity (10 ? 40 mEq/L)
sum total of free and combined study.
it is measured by titration with NaOH by
phenophthalein indicator
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
(Ewald meal: toast, with water or tea Fractional test
meal of Rehffus: Pint of oat meal gruel)
Analysis of samples
Hyperacidity/
.
Max free acidity
Duodenal ulcer
hyperchlorhydria
exceeds 45 mEq/L
Gastric ulcer
Gastric carcinoma
Hyperirritability
Hypoacidity
Free acid below the
Pernicious anemia
normal range
Achlorhydria
No secretion of HCl
Carcinoma stomach
but enzyme pepsin is
Partial gastrectomy
present
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 cord
Stimulation tests ?
1. Alcohol stimulation test
Overnight fast, Ryles tube passed ? 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
2. Caffeine stimulation Test
caffeine sodium benzoate (500 mg in 200 ml water) given
orally
3. 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
.
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
4. 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 ? 0.1-0.2U/kg body weight of soluble
insulin iv
After successful vagotomy , since there is no response
to insulin, gastric acidity remains at a low level of 15
-20 meq/L before as well as after insulin
administration.
5.Pentagastrin stimulation test
? Pentagastrin is a synthetic peptide.
? It stimulates the gastric secretion in a manner
similar to the natural gastrin.
? The stomach contents are aspirated by Ryle's
tube in a fasting condition.
? This is referred to as residual juice.
? The gastric juice elaborated for the next one
hour is collected and pooled which represents
the basal secretion.
.
? Pentagastrin (6 micg/kg body wt given sc) is
now given to stimulate gastric secretion.
? The gastric juice is collected at 15 minute
intervals for one hour.
? This represents the maximum secretion.
? Each sample of the gastric secretion collected
is measured for acidity by titrating the samples
with N/10 NaOH to pH 7.4.
? The end point may be detected by an indicator
(phenol red) or a pH meter
.
Basal acid output (BAO) refers to the acid
output (millimol per hour) under the basal
conditions i.e. basal secretion.
Maximal acid output (MAO) represents the
acid output (millimol per hour) after the
gastric stimulation by pentagastrin i.e.
maximum secretion.
? In normal individuals,
BAO is 1- 2.5 mmol/hr
MAO is 20-40 mmol/hr.
Condition
.
Basal secretion
Maximal scretion
Normal
1 ? 2.5 mEq/hr
20 ? 40 mEq/hr
Duodenal ulcer
Moderately raised
Above 40 mEq/hr
Zollinger Ellinsons Highly raised
Highly raised
Syndrome
Gastric cancer
True achlorhydria
Pernicious anemia
True achlorhydria
Tubeless gastric analysis
? The tubeless gastric analysis involves
administration of a cation exchange resin
tagged with a dye Azure A is given orally.
HCl secreted by stomach displaces the dye
Absorbed in intestine
Excreted in Urine
The amount of dye excreted in urine is
proportional to acid output.
Helicobacter Pylori Detection
? H.pylori infection is playing a role in acid peptic disease.
? The bacteria releases Urease enzyme
Tests for H.Pylori
1. Rapid urease test in gastric biopsy
2. Serological tests ? anti H.Pylori antibody ,less reliable
3.
13 C, 14 C- Urea breath CO2 test
4. Stool antigen for H.Pylori
5. Histological examination and culture of gastric biopsy
sample.
ENDOSCOPY
Importance
Limited but specific uses in certain conditions
Perinicious anaemia
ZES
Peptic ulcer
Now endoscopy plays a major role
Biopsy can be taken
This post was last modified on 30 November 2021