Biochemical tests

of gastrointestinal

tract.

STOMACH FUNCTION

GASTRIC DISEASES :

Peptic ulcer

Most peptic ulcer associated with H. pylori infection

the organism is present in the mucosa and its protect

from stomach acidity by creation of more neutral

microenvironment through secretion of large

amount of urease enzyme.

ZOLLINGER –ELLISON DISEASE

Ectopic secretion of gastrin (gastinoma).

That is neoplasia of either pancreatic gastrin producing cell

or gastric gastrin producing cell.

Increase gastrin production lead to chronic hyper secretion

of gastric acid .

Pernicious anemia:

is one of many types of the larger family of megaloblastic

anemias. It is caused by loss of gastric parietal cells, which

are responsible, in part, for the secretion of intrinsic factor,

a protein essential for subsequent absorption of vitamin

B12 in the ileum.

GASTRIC FUNCTION TESTS

PENTAGASTRIN TEST

Measurement of the amount of HCl

produced by the stomach without

exposure to visual, auditory or

olfactory stimuli.

A. BASAL GASTRIC SECRETION

One hour morning aspiration

Following a 12 hour overnight fast, the patient is

intubated under fluoroscopic guidance

Basal juice

B) Pentagastrin stimulation test

Pentagastrin is a synthetic pentapeptide containing

the four C-terminal amino acids of gastrin coupled

to alanine. It has biologic activity similar to gastrin,

stimulating HCl and pepsin secretion.

is injected subcutaneously (4 µg/kg).

Collect the second aspiration .

Maximum

secrotary

INTERPRETATION :

Low HCL low HCL (pernicious anemia)

Low HCL high HCL (mucosal peptic ulcer

high HCL high HCL (ZE

M Sbasal

UREA BREATHING TEST (H. PYLORI):

A BASELINE BREATH SAMPLE IS REQUIRED BEFORE TAKING THE ISOTOPE-LABELED

UREA

Prepare the solution of isotope-labeled urea

Patient drinks the solution. The patient drink the solution using the

plastic straw provided.

Wait 15 minutes, then collect second breath sample in the bag

PANCREATIC FUNCTIONS :

when acid Content reach the duodenum stimulate the

duodenal S cells to release secretin into the blood, which

signals the ductul cells of the small ducts of the pancreas to

secrete a large volume of bicarbonate-rich, clear, watery

fluid called

(hydraulic secretion).

Similarly, the postprandial increase in amino

acids and fatty acids in the duodenal fluid stimulate

the I cells of the duodenum to secrete cholecystokinin

(CCK, aka pancreozymin). CCK, in turn, signals the

acinar cells of the pancreas to release enzyme-rich

fluid into the pancreatic duct. This is so called( ecbolic

Secretion).

ACUTE PANCREATITIS

Acute pancreatitis is a sudden inflammation that

occurs over a short period of time. In the majority

of cases, acute pancreatitis is caused by

gallstones or heavy alcohol use

Is ultimately caused by auto digestion of

pancreases

Chronic pancreatitis:

occurs most commonly after an episode of acute

pancreatitis and is the result of ongoing

inflammation of the pancreas.

In about 45% of people, chronic pancreatitis is

caused by prolonged alcohol use. Other causes

include gallstones, hereditary disorders of the

pancreas, cystic fibrosis

CYSTIC FIBROSIS :Inherited autosomal recessive genetic Disorder

Cystic fibrosis (CF) occurs when the gene

responsible for manufacturing an chloride ion

channel becomes mutated, causing the gene to

work abnormally. This channel creates

mucus, digestive juices and sweat. When this gene

mutates it tells the body to produce thick, sticky

mucus which promotes sinus conditions.

SECRETIN AND CCK TEST :

The secretin / cholecystokin-pancreozymin test to

assess pancreatic exocrine function.

Method

Overnight fasting patient

Collect the basal juice

Pancreatic secretion is stimulated by intravenously

administrated of secretin in a dose varying from 2-

3U\Kg of body weight

After of 20min of secretin injection administrated of

CCK and after 1h collect the pancreatic juice

Then the PH ,volume ,HCO3 level and enzymes activity are

determined .

Decrease pancreatic fluid with increase enzyme activity is

associated with pancreatic obstruction

Low concentration of HCO3 with low enzyme is associated

by cystic fibrosis or chronic pancreatitis

Xylose absorption test.

Fecal fat determination

Serum amylase

Sweet test (cystic fibrosis)

OTHER PANCREATIC FUNCTION:

INTESTINAL FUNCTION

MALDIGESTION / MALABSORPTION

Maldigestion describes the inability of an individual

to digest food in the gut .

malabsorption is the inability to absorb nutrients

which have been digested from food through the

gut .

Celiac disease is an immune reaction to eating

gluten, a protein found in wheat.that damages

the small intestine's lining and prevents

absorption of some nutrients (malabsorption).

XYLOSE ABSORPTION TEST

Xylose is pentose sugar is ordinarily not present in

the blood. Pentose sugars Are absorbed un

changed by small intestine .

The test is done by ingestion of 25g dose by fasting

adult half of ingested xylose lose by the action of

bacteria and anther half excreted unchanged in the

urine .

So before making the test must be sure the normal

function of kidney .

After ingestion collected one or more than one of

blood samples(30m,1h.2h)

And collected the urine sample after 5h of ingestion

Then measured the xylose in the plasma and urine

sample by heating of protein free supernates of

urine and plasma to convert xylose to furfural with

is then react with p-bromoaniline to form a pink

product the absorbance measured in 250nm and

thiourea is add as an antioxidant to prevent the

information of interfering chromogene.

Interpretion

↑p ↑p) Normal (

Intestinal malabsorption (↓P ↓U)

Renal “retention” (renal failure) (nl or ↑P, ↓U)

FECAL FAT ANALYSIS

Fecal fat drivedfrom four source

Unabsorbed in gested lipid , lipid excreted to the intestine

from the bile,cell shed into the intedtine and metabolism of

intestinal bacteria.

The fecal fat dose not normally exceed that 7g in

24hperiod

Increse fecal fat can be caused by biliriiy obestruction ,

sever steatorrhea associated with pancreatic exocrine

insuffinency or disease of small intestine

Normal fecal lipid is comoped of about 60% fatty acid ,

30%sterole and carotenoid and 10% triglyceride with small

amount of cholestrol and phosphlipid .

Qulative screeing test for fecal fat

Screeing test for detection steatorrhea this test commonly

used fat soluble stain ( sudan 3, sudan5,oil redOand blue

nile)which dissolved in and colour the lipid droplets

Quantitative fecal fat analysis

Usually on 72-hour stool collection and may

increase to 5 day.

Gravimetric method for fecal fat analysis

The entire sample is emulsified with water and liquid

is acididified to convert all fatty acid soap to free

fatty acid followed by extraction of lipid into a

organic solvent and then evaporations of the

organic solvent and the lipid residue is weighted.

OTHER TEST

Lactose tolerances test

Serum caotenoid

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Directed by

Sara abdel mahmoud omer