Transcript
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
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