Download MBBS Gastric Function Tests I Lecture PPT

GASTRIC

FUNCTION TESTS

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DR . SUDHANSHU SHEKHAR

ASSOCIATE PROFESSOR

DEPT. OF BIOCHEMISTRY

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Indications of gastric function tests

1. Diagnosis of gastric ulcer
2. In chronic duodenal ulcer
3. Evaluate pernicious anemia in adult

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4. Presumptive diagnosis of Zollinger ? Ellison

syndrome

5. Determination of completeness of surgical

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vagotomy
CLASSIFICATION

1.Examination of resting contents in resting juice

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(GASTRIC RESIDUM )

2.Fractional test meal
3.Examination of contents after stimulation

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a) Alcohol stimulation
b) Caffeine stimulation
c) Histamine stimulation
d) Augmented histamine test
e) Insulin stimulation test

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f) Pentagastrin test
4.Tubeless gastric analysis
5. Endoscopy
Collection of sample

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Collection of contents of stomach
? After overnight fast
? After test meal
Types of stomach tubes
Rehfuss tube

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Ryles tube
Markings on tube
Single ring reaches lips ----Tip reaches cardiac end
Double ring reaches lips--- Tube in body of stomach

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Examination of resting contents

1.Volume
Normal ----20 ? 50 ml
Abnormal -----greater than 100 ? 120 ml

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Hypersecretion of gastric juice
I. Retention of gastric contents due to delayed

emptying

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II. Due to regurgitation of duodenal contents
2. Consistency
Normal -----fluid
Abnormal ----food residues ( Ca stomach)
.

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3.Colour
Normal -----clear or colourless
Abnormal ------
slightly yellow /green -- regurgitation of bile

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red brown--- due to presence of blood

4.Bile
Intestinal obstruction
Ileal stasis

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.

5.Blood
In trace amount ? may be due to trauma during

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Ryles tube passage

Increased amount ?
Gastric carcinoma
Erosive gastritis

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Bleeding peptic ulcer
6. Mucus
Normal --- small amount
Increased mucus ----gastritis and gastric

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carcinoma
.

7. Organic acids
Absence of HCl ------micro organisms thrive and

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ferment food residues to produce organic acids,
lactic acid and butyric acid

8. Pepsin

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Absence ---Achylia Gastrica
Incresed --- Z E syndrome
duodenal ulcer
gastritis
Decresed --- chief cell mass

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atrophic gastritis
gastric carcinoma
9. FREE AND TOTAL ACIDITY

Free acidity (0 ? 30 mEq/L)

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measures only HCl
it is measured by titration with N/10 NaOH using

Topfer's reagent as indicator

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Combined acidity ( FA-TA)
include Protein hydrochlorides, acid phosphates, and

organic acids like lactic acid and other organic acids

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Total Acidity (10 ? 40 mEq/L)
sum total of free and combined study.
it is measured by titration with NaOH by

phenophthalein indicator

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Fractional gastric analysis/fractional

test meal

Introduction of ryles tube in stomach of fasting

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patient Removal of residual gastric contents and its
analysis

Ingestion of test meal

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(Ewald meal: toast, with water or tea Fractional test

meal of Rehffus: Pint of oat meal gruel)

Analysis of samples

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Hyperacidity/

.

Max free acidity

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Duodenal ulcer

hyperchlorhydria

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exceeds 45 mEq/L

Gastric ulcer
Gastric carcinoma
Hyperirritability

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Hypoacidity

Free acid below the

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Pernicious anemia

normal range

Achlorhydria

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No secretion of HCl

Carcinoma stomach

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but enzyme pepsin is

Partial gastrectomy

present

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Pernicious anemia
Hyperthyroidism
myxedema

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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

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Stimulation tests ?

1. Alcohol stimulation test

Overnight fast, Ryles tube passed ? resting

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contents removed for analysis


100 ml of 7% ethyl alcohol is administered

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Samples removed after every 15 mins and analysed

for free and total acidity, presence of bile, blood

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and mucus
2. Caffeine stimulation Test

caffeine sodium benzoate (500 mg in 200 ml water) given

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orally

3. Histamine stimulation test
Powerful stimulant for HCl in normal stomach
Acts on receptors of oxyntic cells, increasing cAMP,

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which causes secretion of increased volume of high

acidic gastric juice with low pepsin content

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Best to differentiate between true achlorhydria from

false achlohydria

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.

Augmented histamine test
? Normal persons ---Upto 10 mEq/hr acid is

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present in pre histamine specimen ,

with 10 -25 mEq in post histamine

specimens

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Pernicious anemia ----No free HCl secreted
Duodenal ulcer ----- > 100 meq
4. Insulin stimulation test (Hollander's test)

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Potent stimulus for gastric acid secretion ?

hypoglycemia

Indication :

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To check the effectiveness of vagotomy in patients

with duodenal ulcer

Stimulus ? 0.1-0.2U/kg body weight of soluble

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insulin iv

After successful vagotomy , since there is no response

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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.

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? It stimulates the gastric secretion in a manner

similar to the natural gastrin.

? The stomach contents are aspirated by Ryle's

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tube in a fasting condition.

? This is referred to as residual juice.
? The gastric juice elaborated for the next one

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hour is collected and pooled which represents
the basal secretion.
.

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? Pentagastrin (6 micg/kg body wt given sc) is

now given to stimulate gastric secretion.

? The gastric juice is collected at 15 minute

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intervals for one hour.

? This represents the maximum secretion.
? Each sample of the gastric secretion collected

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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

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(phenol red) or a pH meter
.

Basal acid output (BAO) refers to the acid

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output (millimol per hour) under the basal
conditions i.e. basal secretion.

Maximal acid output (MAO) represents the

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acid output (millimol per hour) after the
gastric stimulation by pentagastrin i.e.
maximum secretion.

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? In normal individuals,
BAO is 1- 2.5 mmol/hr
MAO is 20-40 mmol/hr.
Condition

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.

Basal secretion

Maximal scretion

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Normal

1 ? 2.5 mEq/hr

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20 ? 40 mEq/hr

Duodenal ulcer

Moderately raised

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Above 40 mEq/hr

Zollinger Ellinsons Highly raised

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Highly raised

Syndrome

Gastric cancer

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True achlorhydria

Pernicious anemia

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True achlorhydria
Tubeless gastric analysis

? The tubeless gastric analysis involves

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administration of a cation exchange resin
tagged with a dye Azure A is given orally.

HCl secreted by stomach displaces the dye

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Absorbed in intestine

Excreted in Urine
The amount of dye excreted in urine is

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proportional to acid output.
Helicobacter Pylori Detection

? H.pylori infection is playing a role in acid peptic disease.
? The bacteria releases Urease enzyme

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Tests for H.Pylori
1. Rapid urease test in gastric biopsy
2. Serological tests ? anti H.Pylori antibody ,less reliable
3.

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13 C, 14 C- Urea breath CO2 test

4. Stool antigen for H.Pylori
5. Histological examination and culture of gastric biopsy

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sample.

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ENDOSCOPY
Importance

Limited but specific uses in certain conditions

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Perinicious anaemia

ZES
Peptic ulcer
Now endoscopy plays a major role

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Biopsy can be taken