Download MBBS Gastric Function Tests I Lecture PPT

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