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SEM3: PATH30200 GI/GU Illness > L6 Malabsorption and Small Intestine Neoplasms > Flashcards

L6 Malabsorption and Small Intestine Neoplasms Flashcards

1
Q

Specific vs. Generalized Malabsorption?

A

*Generalized malabsorption–absorption of several or all major nutrient classes is impaired

*Specific malabsorption–identifiable molecular defect that causes malabsorption of a single nutrient

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2
Q

Malabsorption results from a disturbance in at least one of the four phases of nutrient absorption. What are these 4 stages?

A
  1. intraluminal digestion (emulsification helps)
  2. terminal digestion (brush border)
  3. transepithelial transport
  4. lymphatic transport of absorbed lipids.
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3
Q

Causes of Malabsorption (7)

A
  1. Defective Intraluminial Digestion
  2. Primary Mucosal Cell Abnormalities
  3. Defective Epithelial Transport
  4. Reduced Small INtestinal Surface Area
  5. Lymphatic Obstruction
  6. Infection
  7. Latrogenic
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4
Q

Example of Malabsorption caused by Disaccharide Deficiency?

A

Lactose Intolerance
Congenital -Rare
Acquired-Common post viral/bacterial infection

Bacterial fermentation of the unabsorbed sugars => increased hydrogen production =>measured in exhaled air by gas chromatography

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5
Q

Example of malabsorption caused by Defective Epithelial Transport?

A

Abetalipoproteinemia

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6
Q

Pathogenesis of Abetalipoproteinemia?

A

Faulty microsomal triglyceride transfer protein (MTP) gene
=> Impaired transepithelial transport of lipids from enterocytes to blood

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7
Q

Symptoms of Abetalipoproteinemia?

A

Steatorrhoea (Fatty Stools)
Diarrhoea
Lipid vacuoles visible in enterocytes
Failure to thrive

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8
Q

Malabsoprtion conditions caused by Reduced Small Intestinal Surface Area?

A

Crohn’s Disease
Mucosal inflammation
Scarring
Fistulas
Common post-surgery Granulomas -TB

Coeliacs Disease
abnormal immune reaction to gluten
=> damage to the surface enterocytes of the small intestine
=> severely reduces their absorptive capacity

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9
Q

Presentationn of Coeliac’s DIsease?

A

Diarrhoea/Steatorrhoea
Flatulence
Weight loss
Fatigue

EASY TO MISS: Majority of pts. Expressed mild, non-specific symptoms of Bloating/indigestion
Aymptomatic w/ unexplained iron deficiency anemia

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10
Q

Tissue injury in Coeliac’s Disease is primarily a result of ____________

A

Tissue injury primarily result of immune response
◊ Perturbed T-Cell function
◊ Genes cause amplified immune response (IL-2, 21)

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11
Q

Due to high _________content many gluten peptides are resistant to intestinal peptidases

A

Due to high proline content many gluten peptides are resistant to intestinal peptidases

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12
Q

__________ => post epidemic coeliac surge

A

Intestinal viral infections => post epidemic coeliac surge

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13
Q

Roles of Gliadin/Glutenin in Coeliac Disease

A

Gliadin/Glutenin: Direct effects on intestinal permeability through the disruption of tight junctions between enterocytes => gluten exposure to immune system

Gliadin: glutamine allows it to react w/ tissue transglutaminase => Potent T-CELL Activator

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14
Q

What occurs to Jejunal Mucosa in Coeliac’s Disease?

A

Total Villous Atrophy

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15
Q

Where is Coeliac’s Disease most severe?

A

proximal small intestine: duodenum and proximal jejunum

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16
Q

Clinical Associations of Coeliac’s Disease?

A

Skin blistering ‘dermatitis herpetiformis’: IgA against epidermal transglutaminase similar to tissue transglutaminase
Splenic atrophy
Atopy and Autoimmune disease

17
Q

Complications of Coeliac’s Disease?

A

Ulceration of small intestine from chronic ulcerative enteritis
Increased risk of GI Adenocarcinomas + Intestinal Lymphoma
Esophageal squamous cell carcinoma (50-100x)
Osteoporosis, Muscle wasting, dental enamel hypoplasia

18
Q

Diagnosis of Coeliac’s Diseease

A

Detection of circulating tissue transglutaminase or anti-endomysial antibodies strongly favors the diagnosis
Definitive diagnosis rests upon:
◊ Clinical documentation of malabsorption
◊ Histological confirmation on small bowel biopsy
◊Symptomatic and mucosal histology improvement upon gluten withdrawal from diet

19
Q

Causes of Lymphatic Obstruction leading to Malabsoprtion?

A

Lymphoma
TB

20
Q

Parasitic Infection leading to Malabsorption

A

Giardiasis
Trophozoites
pear shaped w/ 2 nuclei
Cause of traveler’s Diarrhea (Contaminated water)

21
Q

Tropical Sprue Characteristics/Treatment

A

Characterized by:
chronic diarrhea, weight loss, lethargy, malaise
macrocytic anemia due to folate or vitamin B12 deficiency

Looks like coeliac disease but DOESN’T respond to gluten restriction

Treatment:
May be relieved by tetracyclines

22
Q

Whipple Disease Characteristics/Treatment

A

Rare bacterial infection

Lymphadenopathy, CNS + Joint Symptoms

Infiltration of lamina propria with FOAMY MACROPHAGES with abundant PAS(d)+

Treatment:
prolonged cephalosporin and co-trimoxazooe

23
Q

Latrogenic Causes of Malabsorption

A

i. Subtotal gastrectomy (B12)
ii. Short gut syndrome, following extensive surgical resection
iii. Distal ileal resection or bypass
iv. Radiation enteropathy

24
Q

Excessive fecal fat and bulky, frothy, greasy, yellow or clay-colored stools

Significance?

A

Steatorrhea: excessive fecal fat and bulky, frothy, greasy, yellow or clay-colored stools

hallmark of malabsorption

25
Q

Short stature due to growth arrest from energy/protein deficiency

A

Marasmus

26
Q

Adequate energy, poor protein intake

A

Kwashiorkor

27
Q

Common Malignancies of Small intestine

A

Adenomas and adenocarcinomas are RARE, common in Large bowel

Neuroendocrine cell tumours + Lymphomas relatively more common in small

28
Q

Presentation/Associations of Small Intestinal Adenocarcinoma

A

Majority in Duodenum
Cause Obstructive Jaundice

Chronic Inflammation from Crohn’s Disease is major risk factor

29
Q

Carcinoid (Neuroendocrine) Tumors occur most Commonly in ___________ and __________ metastasize

A

Carcinoid (Neuroendocrine) Tumors occur most Commonly in Appendix and RARELY metastasize

30
Q

Condition resulting from tumor secretion of serotonin often seen w/ hepatic metastasis?

How is it Diagnosed?

A

Carcinoid Syndrome

Diagnosed by excess 5HIAA in urine

31
Q

Risk factor for Gastrointestinal Lymphoma?

A

Chronic gastritis caused by H. Pylori

32
Q

Characteristics/Risk Factor/Diagnosis of Immunoproliferative small intestinal disease (IPSID)

A

Distinguished by malabsorption, anorexia and FEVER

Also known as α heavy chain disease - IgA heavy chain fragments on electrophoresis

Associated with Campylobacter JEJUNI

SEM3: PATH30200 GI/GU Illness (5 decks)

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