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What is the primary role of biochemical tests in the investigation of GI tract disease?
Gastrinoma is caused by a neoplasia of pancreatic gastrin-producing cells.
True
What is the primary cause of chronic pancreatitis?
Advanced stages of pancreatic disease
Elastase is a ______ enzyme that is not degraded in the intestine.
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Match the following investigative techniques with their corresponding uses:
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What is the main cause of acute pancreatitis?
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What is the significance of a 2-fold increase in plasma gastrin levels after secretin injection?
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Elevated fasting plasma gastrin levels are indicative of Zollinger-Ellison syndrome.
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Calprotectin is a protein derived from activated neutrophils as a result of inflammation.
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What is a consequence of bacterial colonization in the small intestine?
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Match the following investigations with their respective conditions:
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The glucose hydrogen breath test measures the production of _______________ in the intestine.
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What is the name of the autoimmune disorder triggered by a sensitivity to gliadin (gluten protein)?
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What is the result of testing for faecal occult blood (FOB) in asymptomatic populations?
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What is the name of the protein that resists degradation in the gut and can be detected in faeces, which is used as a marker of inflammation?
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Low immunity leads to aerobic bacterial colonization.
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Study Notes
Gastrointestinal Tract Disease
Stomach – Peptic Ulcer
- Helicobacter pylori (H.pylori) causes peptic ulcer disease and can be diagnosed using:
- Urea breath test
- Serological tests
- Faecal antigen testing
- Urea breath test:
- H.pylori produces urease enzyme, which converts urea into ammonia and carbon dioxide
- Expired isotopically labelled CO2 is collected and quantified
Stomach – Zollinger-Ellison Syndrome
- Caused by gastrinoma: a neoplasia of either gastric gastrin-producing cells or pancreatic gastrin-producing cells (more common)
- ↑ Gastrin secretion leads to:
- Chronic hypersecretion of gastric acid → peptic ulceration
- Acidity (↑ [H+]) → ↓ pancreatic lipase → fat malabsorption → steatorrhoea
- Diagnosis of gastrinoma: based on elevated fasting plasma [gastrin] in the presence of gastric acid hypersecretion
- Procedure:
- Stop proton pump inhibitors (PPIs) and H2-receptor blockers
- Give IV injection of secretin:
- If 2-fold increase in plasma [gastrin] → gastrinoma
- If no change → G-cell hyperplasia
Pancreas – Acute Pancreatitis
- Mainly due to:
- Gallstones
- Alcoholism
- Infection
- Amylase arises mainly from:
- The pancreas (P-isoamylase)
- The salivary glands (S-isoamylase)
- Serum P-isoamylase activity is more specific to acute pancreatitis
- Serum total amylase > 10 times normal value → acute pancreatitis
Pancreas – Chronic Pancreatitis
- Chronic pancreatitis (advanced stages) → impaired secretion of pancreatic enzymes → malabsorption and steatorrhoea
- Diagnosed by pancreatic imaging techniques
- Elastase:
- A pancreas-specific enzyme that is not degraded in the intestine
- High concentration in faeces
- Low faecal elastase → severe pancreatic insufficiency
Small Intestine – Bacterial Colonisation
- Mainly due to:
- Intestinal stasis (e.g. blind loop, stricture)
- A colonic fistula
- Low immunity → anaerobic bacterial colonisation
- Consequences:
- Bile salt deficiency
- Decreased micelle formation
- Vitamin B12 deficiency
- Investigation:
- Culture of small bowel aspirate
- Glucose hydrogen breath test:
- Bacteria ferment carbohydrates, producing hydrogen
- Hydrogen is not produced by mammalian cells
- Test is not sensitive, but helpful
Small Intestine and Colon – Celiac Disease
- Celiac disease: an autoimmune disorder, triggered by a sensitivity to gliadin (gluten protein)
- First-degree relatives of an affected patient have ↑ risk
- Also, other autoimmune diseases like DM type-1 and autoimmune thyroiditis
- Diagnosis:
- Small intestine biopsy
- Serological tests: circulating antibodies to tissue transglutaminase (tTG) → test for anti-tTG IgA
Small Intestine and Colon – GI Inflammation
- Calprotectin:
- A calcium-binding protein, derived from activated neutrophils as a result of inflammation
- Resists degradation in the gut, and can be detected in faeces
- Highest levels: in inflammatory bowel disease and bacterial infection
- Increased levels: colon and stomach cancer, colonic polyps and diverticular disease
- Presence: irritable bowel syndrome (IBS)
Small Intestine and Colon – Faecal Occult Blood
- Testing for faecal occult blood (FOB) is a tool for screening asymptomatic populations of bowel cancer
- This screening results in a 16% reduction in the relative risk of colorectal cancer mortality
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Description
This quiz covers the diagnostic tests used to investigate gastrointestinal tract diseases, including biochemical tests, microbiological investigations, and more. Learn about the different tests used to diagnose stomach diseases, including peptic ulcer and Helicobacter pylori.
