clinical biochem

1. Jimma University
Institute of Health Sciences
Department of Biochemistry
Course Title: Clinical bioch
Seminal Presentation on- GIT Function test
By;- Getahun Alega…RM0877/15-0
Submitted to:-Dr.Tesaka (ass;t professor )
1
3/19/2024

2. Learning objectives
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To understand:
✔ Some of the gastric and pancreatic function test ;
✔ tests of intestinal function;
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3. Introduction
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 Stomach is a reservoir of ingested foodstuffs.
 It has a great churning ability which promotes digestion.
 Stomach elaborates HCI & proteases (pepsin) which are responsible
for the initiation of digestive process.
 The products obtained in the stomach (peptides, amino acids)
stimulate the release of pancreatic juice & bile.
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4. Normal healthy stomach
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 In 24 hours: gastric juice secretion
• Fasting: 1000 ml
• Normal diet : 2000 to 3000 ml.
 The chief constituents of gastric juice are:
• HCL
• Pepsinogen pepsin
• Rennin in infant
• Intrinsic factor
• Mucous
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5. Secretion of gastric HCL
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 The parietal (oxyntic) cells of gastric glands produce HCL.
 The pH in the gastric lumen is as low as 0.8 (against the blood pH 7.4).
 The protons are transported against concentration gradient by an active
process.
 The enzyme K+ activated ATPase-present in the parietal cells is connected
with the mechanism of HCI secretion.
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6. Cont…
6
 It involves an exchange of H+ ions (of the parietal cells) for K+ ions
(of the lumen).
 This is coupled with the consumption of energy/ supplied by ATP.
 The H + are continuously generated in the parietal cells by the
dissociation of carbonic acid which, in turn, is produced from CO2
and Water.
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7. Cont…
7
 The bicarbonate ions (HCO3- ), Iiberated from the carbonic acid
(H2CO3) dissociation, enter the blood in exchange for Cl ions.
 The latter diffuse into the gastric lumen to form HCL.
 Gastrin-a peptide hormone of gastrointestinal tract-stimulates HCI
secretion
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8. Normal HCL secretion
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9. Cont…
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10. Cont…
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 Several test for gastric function evaluation
1. Fractional meal test
2. Alcohol test meal.
3. Penta gastrin stimulation test
4. Augmented histamine test meal
5. Insulin stimulation test [Hollander test meal].
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11. Resting gastric juice [ after fasting]
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• Volume:
• Consistency
• Color
• Bile
• Blood
• Mucous
• Free and total acid
• Organic acid.
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12. Cont…
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• Volume:
• normal after fasting 20-50 ml onlyif 100-120 ml[ hypersecretion, retention or
regurgitation]
• Consistency:
• Normal resting contentfluid and small mucousno food  food residue in gastric
carcinoma.
• Color:
• Mostly clear/colorless sometime due to bile yellowish
 /green and brownish and dark red due to RBCS
• Bile:
• Small amount due to regurgitation from duodenum but more seen in intestinal obstruction.
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13. Cont…
13
• Mucus:
• Only small amount
• Increased in gastritis and gastric carcinoma.
 Free and total acid
• free HCl
• Total: protein hydrochloride and any organic acids
• Free acid: 0 to 30 mEq/L
• Total acid:10 mEq/L higher(10 to 40mEq/L)
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14. Fractional Meal Test (FMT)
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 Fractional test meal involves the collection of stomach contents by Ryle's tube in
fasting.
 This is followed by a gastric stimulation, giving a test meal (rice gruel, black coffee
etc.).
 The stomach contents are aspirated by Ryle's tube at different time periods (every 15
min for 2 hrs.)
 The samples are analyzed for free & total acidity.
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15. Alcohol test meal
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 In this case, the test meal in the form of 100 ml of 7%alcohol is
administered.
 The response to alcohol test meal is more rapid & test time can be
reduced to 1½ hour.
 Clear specimens can be collected by this test & the free acidity levels
are relatively higher compared to FTM.
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16. Pentagastrin stimulation test
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 Pentagastrin is a synthetic peptide.
 It stimulates the gastric secretion in a manner similar to the natural
gastrin.
 The stomach contents are aspirated by Ryle's tube in a fasting
condition.
 This is referred to as residual juice.
 The gastric juice elaborated for the next one hour is collected and
pooled which represents the basal secretion.
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17. Cont…
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 Pentagastrin (5mg/kg body weigh) is now given to stimulate gastric
secretion.
 The gastric juice is collected at 15 minute intervals for one hour.
 This represents the maximum secretion.
 Each sample of the gastric secretion collected 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 (phenol red) or a pH
meter
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18. Cont…
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 Basal acid output (BAO) refers to the acid output (millimol per hour)
under the basal conditions i.e. basal secretion.
 Maximal acid output (MAO) represents the acid output (millimol per
hour) after the gastric stimulation by pentagastrin i.e. maximum secretion.
 In normal individuals, the BAO is 4-10 mmol/hr while the MAO is 20-50
mmol/hr.
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19. Augmented Histamine Test
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• All the process is same as Penta gastrin stimulation test except.
• Histamine [ 0.04 mg/kg body weight] is given subcutaneously
• Acts on the H2 receptor of parietal cell increases cAMP level
increases HCL secretion.
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20. Insulin test meal
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 This is also known as Hollander's test.
 It is mainly done to assess the completeness of vagotomy (vagal
resection).
 Insulin (0.1 unit/kg body weight) is administered intravenously,
which causes hypoglycemia, usually within 30 minutes, in normal
persons.
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21. Cont…
21
 If the vagotomy operation is successful, insulin administration does
not cause any increase in the acid output, compared to the basal level.
 This test has to be carefully perfomed, since hypoglycemia is
dangerous.
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22. Abnormalities of gastric function
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 Increased gastric HCI secretion is found in
 Zollinger-Ellison syndrome (a tumor of gastrin secreting cells of the
pancreas),
 Chronic duodenal ulcer,
 Gastric cell hyperplasia,
 Excessive histamine production etc.
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23. Cont…
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24. Cont…
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 A decrease in gastric HCI is observed in
 Gastritis
 Gastric carcinoma
 Pernicious anemia
 Partial gastrectomy
 Chronic iron deficiency anemia.
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25. Cont…
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26. Cont…
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• Other relevant test:
• H . Pylori test
• Blood test.
• Breath test, also known as a urea breath test.
• Stool
• Endoscopy.
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27. Urea breathe test
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28. Pancreatic function tests
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 Pancreatic function tests can be divided into tests for diagnosing:
 Diseases of exocrine pancreas
 Exocrine pancreatic insufficiency
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29. Cont…
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 Tests for diagnosing diseases of the exocrine portion of the pancreas
are:
 Serum amylase
 Serum lipase
 Sweat chloride
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30. Serum amylase
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 Amylase is a digestive enzyme synthesized in the pancreas and the salivary
glands.
 Most of the amylase present in circulation is of pancreatic origin.
 In acute pancreatitis, amylase leaks into circulation from the damaged
cells.
 Serum amylase is, therefore, greatly increased in acute pancreatitis
 A smaller increase occurs in acute parotitis
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31. Cont…
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 Macroamylasemia is a condition characterized by persistent elevation of
serum amylase activity with no apparent clinical symptoms of pancreatic
disease.
 Amylase complexes with immunoglobulins, which prevents renal
excretion.
 Macroamylasemia by itself is not a disease, but it may be an early marker
of pancreatic disease.
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32. Amylase levels are increased in
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 Acute pancreatitis
 Diabetic ketoacidosis
 Burns Renal failure
 Perforated duodenal ulcer
 Malignancy
 Gall stones
 Ovarian cysts.
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33. Serum lipase
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 Lipase is another digestive enzyme synthesized in the pancreas.
 It leaks into circulation from damaged pancreatic cells in acute
pancreatitis.
 Hence, serum lipase is increased in acute pancreatitis.
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34. Sweat chloride
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 This test is very useful in the diagnosis of cystic fibrosis.
 Cystic fibrosis is also known as fibrocystic disease of the pancreas or muco
viscidosis.
 It is a recessively inherited autosomal disease.
 Very viscous mucus is secreted by exocrine glands in this disease.
 The mucus can clog pancreatic ducts and bronchioles.
 In addition, the chloride content of sweat is increased
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35. Exocrine pancreatic insufficiency
(EPI)
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 The most common causes of EPI are chronic pancreatitis and cystic
fibrosis
 The tests for EPI can be
 direct or
 indirect
 Early EPI is difficult to diagnose by indirect tests
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36. Direct test
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 Oro-duodenal intubation is done to aspirate pancreatic secretion from
duodenum near Ampulla of Vater.
 Secretin or cholecystokinin or both are used to stimulate pancreatic
secretion.
 Pancreatic juice is collected for a period of 45 to 125 minutes.
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37. Cont…
37
 Concentrations of bicarbonate and pancreatic enzymes are measured
in pancreatic juice.
 Low concentrations indicate EPI.
 Indirect tests for EPI are:
 Measurement of faecal fat
 Measurement of faecal elastase
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38. Measurement of faecal fat
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 The patient is placed on a diet having 100 gm of fat per day.
 Stool is collected and fat excretion is measured daily for three days.
 Normal persons excrete less than 7% of the ingested fat.
 In EPI, the excretion of fat is above 20%.
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39. Measurement of faecal elastase
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 Elastase is secreted by the pancreas.
 It is not broken down in the intestines.
 Excretion of < 200 µg of elastase/gm of stool indicates EPI.
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40. Small Intestinal Function Tests
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 Small intestine secretes regulatory molecules and enzymes for
digestion of carbohydrates lipids and proteins.
 The regulatory molecules are secretin, cholecystokinin,vasoactive
intestinal polypeptide.
 Secretin and cholecystokinin stimulate pancreatic secretion.
 Secretin also stimulates gall bladder and gastric secretion.
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41. INTESTINAL ENZYMES
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 Disaccharidases of intestinal mucosal brush border
 Dipeptidases ,Tripeptidases in mucosal cell
 Intestinal lipase in the mucosal cell.
 Absorption
 Fats, proteins, carbohydrates are absorbed in the proximal jejunum.
 Vitamin B12, bile acids are absorbed in the terminal ileum.
 Water and electrolytes are also absorbed by small intestine.
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42. Used to diagnose malabsorption .
To diagnose specific intestinal diseases .
42
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43. FECAL FAT ESTIMATION
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 A collection period of three days
 An average intake of 90 gm fat daily
 Fecal fat is normally less than 7 gm / 24 hours.
 When the feces contain split fatty acids, it indicates normal pancreatic
function but defective absorption.
 If the excreted fat is neutral fat, it is due to defective digestion and in favor
of pancreatic disease.
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44. Con;t…
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45. Con;t…
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46. Lactose tolerance test
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 50 gm lactose is given orally and increase in blood glucose level is
evaluated.
 The lactose tolerance test requires an individual to drink a liquid that
contains lactose.
 Several blood samples are taken over a two hour period
 The blood test is considered abnormal if glucose level rises less than 20
mg/dL (1.1 mmol/L) within 2 hours of drinking the lactose solution.
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47. Lactose breath test
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 14C labeled lactose is given orally and breath 14C labeled CO2 is
estimated.
 In lactose intolerance labeled CO2 will be low.
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48. Con;t…
48
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49. Amino Acids Absorption
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 Specific disorders of amino acid transport affect both proximal
jejunum and proximal renal tubules.
 Eg.Cystinuria, Hartnup disease.
 Diagnosed by chromatography of amino acids in urine samples.
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50. Tests For Gut Permeability
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 Normally lactulose is not absorbed by intestinal mucosal cell whereas
rhammose is well absorbed.
 In case of Celiac disease and Crohn’s disease, there will be increased
absorption of lactulose and decreased absorption of rhammose.
 Alcohol also alters gut permeability and increases the absorption of
endotoxin leading to liver injury.
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51. Reference
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 Text book of Biochemistry – DM Vasudevan
 Text book of Biochemistry – U Satyanarayana
 Text book of Biochemistry – MN Chatterjea
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52. 52
THANKS!!!
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