Download gastric-function

D-GASTRIC FUNCTION
TESTS
In
some diseases of Stomach & Duodenum
alterations in gastric secretion occurs,
thereby
 chemical examination of gastric contents
has limited but specific value in diagnosis &
assessment of disorders of upper GIT.
Hence
to get complete data of gastric fn, the
contents of stomach should be examined
During resting period
During digestion after meals
After stimulation
Gastric juice secreted in 24 hrs is
about 1500 ml to 2000ml.
N
Chief constituents of Gastric juice
 HCl………Parietal cells / oxyntic cells
- it activates the zymogen pepsinogen to pepsin by partial
proteolysis, also helps in absorption of iron and calcium.
 Pepsinogen..........Chief cells
- Pepsins act on proteins and polypeptides & cleave peptide
bonds adjacent to aromatic amino acids

Gastrin: hormone secreted by G cells,
stimulates secretion of HCl.

Intrinsic Factor: Parietal cells, is a
glycoprotein required for absorption of
Vit B 12
Gastric
lipase: Chief cells. Act on
Triglycerides, convert to Fatty acids and
glycerol
Rennin
: is seen in infants but not in adults.
Alkaline
Mucus
Indications of Gastric Function Tests
 To
diagnose Gastric Ulcers
 To exclude the diagnosis of Pernicious
Anaemia & Peptic ulcer in Pt with GU.
 For presumptive diagnosis of Zollinger
Ellison Syndrome
 To determine the completeness of Surgical
Vagotomy.
CLASSIFICATION OF GFTs
Analysis
of Resting contents(Gastric
Residuum)
Fractional Test Meal Analysis
Analysis after Stimulation
# Alcohol stimulation
# Caffeine stimulation
# Histamine stimulation
CONTD……
# Augmented Histamine test
# Insulin stimulation
# Pentagastrin test
Tubeless Gastric Analysis
Other
relevant tests are estimation of Sr.Gastrin, Sr.Pepsinogen levels, Tests for Occult
blood and Tests for H.Pylori
Analysis
1)Volume
of resting contents:
: N20-50ml after a night fast
> 100-120 ml….is abnormal
Volume..
- Hypersecretion of Gastric juice
- Retention due to delayed emptying
- Regurgitation of duodenal contents.
2) Consistency : N Fluid, should not contain
food residues.
3) Colour: N Clear/ Colourless/ slight
yellow/green..
Bright red / dark red / brown…abnormal
dark brown seen in bleeding gastric ulcer,
coffee ground appearance seen in Ca
stomach.
4) Bile: Small amounts are insignificant, but
increased in Intestinal Obstruction / Ileal
Stasis.
5) Mucus: N in small amounts, increased
in gastritis , Ca Stomach.
6) Free & Total Acidity: determined by
titrating a portion of the sample with a
standard solution of NaOH.
Free
acidity measures only HCl, Topfer’s
reagent is used as indicator.
Total
acidity includes HCl and other organic
acids , Phenolphthalein is used as indicator
Normal
values
- Free Acid : 0-30 mEq / L
> 50 mEq / L indicates Hyperacidity
- Total Acid : 10-40 mEq / L
7) Organic Acids: like lactic acid & butyric
acid in large amounts indicate
achlorhydria/hypochlorhydria.
Fractional
Test Meal Analysis
Diff. meals used are
-Ewald test meal (2 pieces toast+250
ml tea)
-Oatmeal porridge
-Riegel meal..not used normally
Procedure:
After removing residual contents,
meal is given. With intervals of 15 minutes
contents of stomach are removed ,strained &
analysed.
Normally
free acid rises steadily from 15
min – ½ hr/45 min, and decreases.
Abnormal
responses are:
1) Hyperchlorhydria / Hyperacidity: when
free acid is > 50mEq / L
Seen in - Duodenal ulcer,
Gastric ulcer,
Gastric cell hyperplasia,
After Gastroenterostomy,
Contd…..
Gastric Neurosis,
Hyperirritability,
Pylorospasm ,
Pyloric Stenosis ,
Chr. Cholecystitis,
Zollinger Ellison Syndrome.
2) Hypochlorhydria / Hypoacidity:
Seen in Ca Stomach , Atonic Dyspepsia
3) Achlorhydria: No HCl is seen but pepsin is
present. Seen in Ca Stomach, Chr.Gastritis,
Partial Gastrectomy, Pernicious Anaemia,
Hyper thyroidism, Myxoedema.
Fractional Test Meal
ACHYLIA
GASTRICA : is a condition
where both enzymes and acids are absent
Seen in – Advanced Ca Stomach
-- Advanced cases of Gastritis
-- Pernicious Anaemia
-- Subacute combined
degeneration of spinal cord.
Analysis after Stimulation :
1)Alcohol
Stimulation :
-stimulant used is 7% ethyl alcohol.
- the residual contents removed after
overnight fasting, 100ml alcohol is given,
samples are taken every 15 min &
analysed for free, total acidity,peptic
activity,blood, bile,mucus.
Advantages
:
- more easy to administer
- consumed better than porridge
- gastric response is rapid
- emptying of stomach is more rapid than
porridge.
Disadvantages:
- stimulus with alcohol is not so strictly
physiological as with oatmeal.
- stimulus is more vigorous compared to
oatmeal
- rather high levels of free acidity seen.
2)
Caffeine Stimulation :
- Caffeine Sodium Benzoate,500mg dissolved in
200ml of water is given.
- Advantages are similar to that of alcohol
stimulation.
3) Histamine Stimulation Test:
- it is a powerful stimulant for secretion of HCl, acts
on oxyntic cells(specific H2receptors )
Indications
: To differentiate “ True “
Achlorhydria from “ False “ Achlorhydria
Types
of Histamine test
- Standard Histamine test
- Augmented histamine test (Kays test).
Standard
Histamine test: SC injection of Histamine 0.01mg/kg
bwt , is given.
# Results
- Absence of HCl…true achlorhydria, seen in pernicious
anemia.
- Increase in HCl…Duodenal Ulcer
Augmented Histamine test (Kays) :
larger dose, 0.04mg/kg b wt of histamine acid phosphate, SC.
Indications:
-to show inability to secrete
acid as in pernicious anemia & subacute
combined degeneration of cord.
- to assess max possible acid secretion in
diagnosis & Surg.Rx of Duodenal ulcer.
Disadv : larger dose causes severe allergic
reactions,hence another antihistaminic
given to prevent.
 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.
Recently,
histamine analogue,called
“Histalog”(3 beta-amino ethyl pyrazole) is
used instead of histamine

recommended dose –10-50mg
No
side effects seen hence no need to use
an antihistamine to block H1 receptors.
Insulin Stimulation test (Hollander’s
test): Hypoglycemia produced by insulin is
a potent stimulus of gastric acid secretion.
 Indications: to see the effectiveness of
vagotomy in pts with duodenal ulcer.
 15units of soluble insulin given IV
 Disadv: Hypoglycemia
 4)

Results: in pts with DU
, before operation
there is marked &
prolonged output of
acid in response to
insulin. After
successful vagotomy,
there is no response
and acid level is very
low.
5)
Pentagastrin test: Pentagastrin, synthetic
peptide, having biologically active sequence
of gastrin.It is “Butyl oxy carbonyl- beta
alanine Trp-Met-Asp-Phe CONH2”
Dose— 6 microgram/kg bwt. SC
 It
is a potent stimulator, causing max
stimulation after assessing basal secretion
rate, hence it is a measure of Total Parietal
Mass.
 Procedure: after removing the residual
contents , the gastric juice secreted for
next 1 hr is collected as a single sample,
which is called BASAL SECRETION.
 Then
pentagastrin is given & 4 samples
are collected with 15 min intervals.
 Basal Acid Output (BAO) is output in mmol
/ hr, in basal secretion.
 Maximal Acid Output(MAO) is output in
mmol/hr, given by sum of the 15 min acid
output after stimulation.
 Peak Acid output (PAO) is output of 2
Consecutive 15 min samples having highest acid
content and the value is multiplied by 2.
Result:
N basal
secretion rate is 1-2.5mEq/hr,
after pentagastrin stimulus..it is 20-40mEq/hr.
- in DU…. 15-83mEq/hr
- in ZE syndrome..basal secretion is > 10 mEq / hr
 Tube
Less 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.
 In
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.
OTHER TESTS:
Serum
Gastrin : is estimated by Radio Immuno
Assay.
level
is
<
10
pico
moles/L,
N
in Zollinger Ellison Syndrome it is > 100
pmol/L.
Serum Pepsinogen :
level is 30-160units/ml
- in pernicious anaemia…very
low/absent
N
- in DU…> 200 units/ml
CONCLUSION
Gastric
Function tests are of limited
but specific value in diagnosing and
assessing some disorders of Upper
GIT.