GASTRIC FUNCTION TEST

Dr. Vijay Marakala, MBBS, MD.

Senior LecturerBIOCHEMISTRY

IMS, MSU.

GASTRIC FUNCTION TESTS

Introduction Indications

Classification

GFT - INTRODUCTION

• Chemical examination of gastric contents has limited but specific value in diagnosis & assessment of disorders of upper GIT

GFT - INTRODUCTION

• Normal fasting gastric juice per day is about 1L

• Stomach of a person taking a normal diet secretes 2L-3L of gastric juice per day

GFT - INTRODUCTION

During resting period

During digestion after meals

After stimulation

Contents of stomach should be examined…

CHIEF CONSTITUENTS OF GASTRIC JUICE

HCl

• secreted by PARIETAL CELLS

Pepsinogen

• Secreted by CHIEF CELLS

Intrinsic factor

• Required for absorption of Vitamin B12

Alkaline mucous

• Which coats the gastric walls act as lubricant

GFT - INDICATIONS

INDICATIONS To diagnose Gastric Ulcers

To exclude the diagnosis of Pernicious anaemia & Peptic ulcer

For presumptive diagnosis of Zollinger Ellison Syndrome

To determine the completeness of Surgical Vagotomy.

COLLECTION OF CONTENTS OF STOMACH – RYLE’S TUBE

GFT – CLASSIFICATIONS

Gastric ResiduumAnalysis of

Resting contents

Fractional gastric analysis using a test ‘meal’Fractional Test Meal Analysis

Stimulation by Alcohol or Caffeine or Histamine or Insulin or Pentagastrin

Analysis after Stimulation

Used as screening testTubeless Gastric

Analysis

ANALYSIS OF RESTING CONTENTS

Volume Consistency Colour Bile

Blood Mucus Pepsin Free acidity

Total acidity Organic acid

ANALYSIS OF RESTING CONTENTSNORMAL ABNORMAL CAUSES

Volume 20-50mL

>100-120mL • Hypersecretion of Gastric juice• Retention due to delayed emptying• Regurgitation of duodenal contents

Consistency - Fluid Food residues • Carcinoma of stomach

Colour – clear- colourless or slightly yellowish or green

Dark red or brown*Due to blood

• Bleeding Gastric ulcer• Carcinoma of stomach

Bile – occasionally Increased amount • Intestinal Obstruction and ileal stasis.

Mucus - small amount Increased amount • Gastritis and carcinoma of stomach

ANALYSIS OF RESTING CONTENTSNORMAL ABNORMAL CAUSES

Organic acid Lactic acid , butyric acid present in large amount

• Hypochlorhydria, achlorhydria and Ca stomach

Free acidity-measures only HCl. 0-30mEq/L

>50mEq/L • Hyperacidity

Total acidity – includes HCl and other organic acids. Normal 10-40mEq/L

Pepsin Decreased levels

Increased levels

• Atrophic gastritis, Ca stomach

• Zollinger-Ellison syndrome

FRACTIONAL TEST MEAL ANALYSIS

Different meals used are

Ewald test meal (2 pieces toast+250 ml tea) Oatmeal porridge

FRACTIONAL TEST MEAL ANALYSIS

• After removing residual contents, meal is given. With intervals of 15 minutes contents of stomach are removed ,strained & analysed

Procedure

• Free acid rises steadily from 15 min – ½ hr/45 min, and decreases

Normal response

FRACTIONAL TEST MEAL ANALYSIS

Hyperchlorhydria

• Free acid >50mEq/L

• Duodenal ulcer• Gastric ulcer• Gastric cell

hyperplasia• Zollinger Ellison

Syndrome

Hypochlorhydria

• Ca of stomach• Atonic

dyspepsia

Achlorhydria

• No HCl but pepsin is present

• Seen in Ca stomach, chronic gastritis

Achylia gastrica

• Both HCl and pepsin are absent

• Later stage of Ca stomach

• Chronic gastritis

• Pernicious anaemia

ANALYSIS AFTER STIMULATION

The residual contents removed afterovernight fasting

7%100ml ethyl alcohol is given

Samples are taken every 15 minAnalysed for free, total acidity, pepsin,

blood, bile and mucus

ALCOHOL STIMULATION

ANALYSIS AFTER STIMULATION

CAFFEINE STIMULATION TEST

Stimulus is caffeine sodium benzoate -500 mg in 200 ml water given orally

ANALYSIS AFTER STIMULATION

Histamine stimulation testPowerful stimulant for HCl in normal stomach

Acts on receptors of oxyntic cells

Best to differentiate between true achlorhydria from false achlohydria

TYPES OF HISATMINE TEST

Standard Histamine

test

Augmented histamine test

(Kay’s test)

HISTAMINE STIMULATION TEST

STANDARD HISTAMINE TEST

Histamine is given subcutaneously 0.01mg/kg body

weight

Absence of HC indicates “achylia

gastrica (true achlorhydria)

Increase in HCl indicates

Duodenal Ulcer

AUGMENTED HISTAMINE TEST (KAYS)

• Procedure: After overnight fast, residual contents are analysed and contents are collected every 20 min for an hr.

• Halfway through this period 4ml of mepyramine maleate (anthisan), given IM, to block H1 receptors.

• At the end of hr histamine acid phosphate,0.04mg / kg bwt, SC given and contents removed every 15 min for 1 hr.

PROCEDURE

AUGMENTED HISTAMINE TEST (KAYS)

Normal response

• Upto 10 mEq/hr acid is present in pre histamine specimens

• with 10 -25 mEq in post histamine specimens

In pernicious anaemia

• No free HCl secreted

In duodenal ulcer

• > 100 meq

INSULIN STIMULATION TEST (HOLLANDER’S TEST)

Hypoglycemia is Potent stimulus for gastric acid secretion

Indication:To check the effectiveness of vagotomy in patients with duodenal ulcer

Stimulus – 15 unit of soluble insulin iv

Results I. Before vagotomy II. After successful

vagotomy, there is no response and acid level is very low.

INSULIN STIMULATION TEST

PENTAGASTRIN TESTSynthetic peptide

It is a potent stimulator

Measure of Total Parietal Mass

Dose— 6 microgram/kg bwt, SC

PENTAGASTRIN TEST - PROCEDURE

After emptying the stomach of

resting contents..

Collect gastric juice secreted for next 1 hr to

have BASAL SECRETION.

Inject pentagastrin

6g/μKg bwt, SC

collect 4 samples with

15 min intervals

Analyse All the specimens

PENTAGASTRIN TEST-CLINICAL SIGNIFICANCE

• Basal secretion rate1-2.5mEq/hr

• After pentagastrin stimulus, it is 20-40mEq/hr

Normal

• 15-83mEq/hr• Mean 43• >40 indicates

duodenal ulcer

In Duodenal ulcer

• Basal secretion is > 10 mEq / hr

in Zollinger-Ellison syndrome

TUBLESS GASTRIC ANALYSIS

It avoids discomfort of naso gastric tube

Used only as a screening test.

Fasting secretion is stimulated by histalogue , after 1 hr dye bound resin “Diagnex Blue” with “ Azure A” is given orally.

TUBLESS GASTRIC ANALYSISIn the presence of HCl resin releases dye,which is

absorbed & later excreted in urine

The quantity of dye in urine provides indication of presence /absence of HCl.

It is not reliable in pts with renal diseases, urinary retention,malabsorption,pyloric obstruction etc.

Thank you

Reference