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GI and metabolism > Malabsorption > Flashcards

Malabsorption Flashcards

1
Q

What is the definition of malabsorption?

A

Defective mucosal uptake and transport of adequately digested protein, fat, carbohydrates or nutrients.

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2
Q

What is intraluminal digestion?

A

Pancreatic enzyme secretion and emulsification by bile salts.

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3
Q

What is terminal digestion?

A

Enzymatic hydrolysis in brush border of small intestine.

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4
Q

What volume of fluid is ingested by the gut per day?

A

2000ml

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5
Q

What is the net excretion of faeces per day?

A

0.1L

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6
Q

What is osmotic diarrhoea?

A

Loose stool that results from a disturbance in electrolyte absorption.

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7
Q

What is steatorrhoea?

A

The presence of excess fat in the faeces.

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8
Q

In what diseases would you see steatorrhoea?

A

Cholestatic liver disease, pancreatitis and coeliac disease

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9
Q

If fat absorption is impaired, what vitamin deficiencies may occur?

A

A, D, E and K

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10
Q

What are potential risk factors for osteoporosis?

A

Anorexia, smoking, alcoholism, steroid therapy, vit D/calcium deficiency.

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11
Q

What happens to bone during osteomalacia?

A

Patients have a normal amount of bone but the mineral content is low.

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12
Q

What is the difference between rickets and osteomalacia?

A

Rickets and osteomalacia have the same cause, but rickets occurs while bones are still growing. Osteomalacia occurs once the epiphyses have fused.

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13
Q

What are the causes of rickets/osteomalacia?

A

Vit D deficiency, inadequate sunlight, coeliac disease, bowel resection, renal disease.

Mildy decreased calcium and phosphate with an increased alkaline phosphatase and parathyroid hormone.

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14
Q

Where is Vit A absorbed and what happens when it is deficient?

A

Small bowel. Xerophthalmia.

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15
Q

Where is Vit B1 absorbed and what happens when it is deficient?

A

Small bowel. Beriberi, Wernicke’s

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16
Q

Where is Vit B2 absorbed and what happens when it is deficient?

A

Small bowel. Angular stomatis, cheilitis.

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17
Q

Where is Vit B6 absorbed and what happens when it is deficient?

A

Small bowel. Polyneuropathy.

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18
Q

Where is Vit B12 absorbed and what happens when it is deficient?

A

Terminal ileum. Pernicious anaemia and subacute degeneration of spinal cord.

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19
Q

Where are Vit B12/IF complexes formed?

A

In the stomach.

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20
Q

What conditions can lead to B12 deficiency.

A

Gastric mucosal atrophy and terminal ileal disease.

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21
Q

Why is B12 required in the diet?

A

Is necessary for the synthesis of DNA in immature RBCs. Deficiency leads to macrocytic anaemia.

22
Q

What are the causes of iron deficiency?

A

Poor iron intake, reduced iro absorption (particularly in duodenum) and increased iron loss (bleeding, sloughed mucosal cells).

23
Q

What is coeliac disease?

A

Inflammatory condition of the small intestinal mucosa induced by an autoimmune reaction to the ingestion of gluten.

24
Q

How common is coeliac disease?

A

1 in 100 in UK

25
Q

What pathologies are found in coeliac disease?

A

Villous atrophy and intraepithelial lymphocytosis.

26
Q

Describe the clinical presentation of coeliac disease in infants.

A

Impaired growth, diarrhoea, vomiting, abdo distension.

27
Q

Describe the clinical presentation of coeliac disease in children.

A

Anaemia, short stature, pubertal delay, rickets, recurrant abdo pain behavioral disturbance

28
Q

Describe the clinical presentation of coeliac disease in adults.

A

Chronic/recurrent iron deficiency, diarrhoea, abdo pain, bloating, isolated nutritional deficiencies, reduced fertility, osteoporosis, osteomalacia, abnormal LFTs

29
Q

What is the average age of coeliac diagnosis?

A

4th-6th decade.

30
Q

How does intestinal inflammation cause malabsorption in coeliac disease?

A

Increased intestinal transit -> reduced macronutrient absorption, negative calorie/protein balance.

31
Q

How does villous atrophy cause malabsorption in coeliac disease?

A

Reduced surface area for absorption

32
Q

What specific nutrient deficiencies are found in coeliac disease?

A

Iron, folate, calcium, vitamins, ADEK and B12

33
Q

How is coeliac disease diagnosed?

A

Clinical history.

Serological tests - endomysial (EMA) and tissue transglutaminase (tTG) antibodies.

Duodenal biopsy via upper GI endoscopy.

34
Q

How is coeliac disease managed?

A

Gluten free diet, repeat biopsy,supplement nutritional deficiencies, monitor bone mineral density

35
Q

Describe the features of Crohn’s disease.

A

Chronic transmural granulomatus inflammatory disorder. May affect any part of the GI tract, often in discontinuity. Twice as common in smokers.

36
Q

What are the clinical features of Crohns disease?

A

Diarrhoea, abdo pain, weigh loss, malaise, nausea, vomiting, perianal disease. Small bowel involvement can lead to malabsorption (iron, folate, vit D). Fistulae, strictures, abcesses, ulceration and perforations.

37
Q

Describe the features of ulcerative colitis.

A

Relapsing and remitting. Involves only the colon and inflammation may be continuous. Starts at the rectum. Only superficial inflammation seen.

38
Q

How would you investigate IBD?

A

Colonoscopy/sigmoidoscopy + biopsies. Rule out infections. Blood tests to correct vitamin/mineral deficiencies. Radiology.

39
Q

How would you manage IBD?

A

Establish severity of disease. Aim for prolonged mucosal healing. Systemic steroids. 5-aminosalicylates. Immunomodulators (azathioprine/mercaptopurine). Biological therapy (infliximab/adalimumab). Nutritional support. Surgery - complications of Crohn’s disease.

40
Q

How does infliximab work?

A

Binds free and transmembrane TNF-alpha - central inflammatory cytokine.

41
Q

What are the consequences of bowel resection?

A

Ileal - B12 deficiency, bile acid malabsorption
Short-bowel syndrome - electrolyte and fluid depletion, (treatment: hypertonic fluids, somatostatin analogues, loperamide)

42
Q

What are the clinical features of chronic pancreatitis?

A

Epigastric pain often radiating to the back, food or alcohol exacerbating the pain, weight loss.

43
Q

What are the causes of chronic pancreatitis?

A

Alcohol (>70%), familial, congenital (pancreas divisum), autoimmune, genetic (eg CFTR)

44
Q

What are the complications of chronic pancreatitis?

A

Exocrine/endocrine insufficiency (eg diabetes), pancreatic duct strictures, jaundice, infection, haemmorrhage, rupture, portal hypertension (ascities/varices), increased risk of cancer.

45
Q

What investigations woulf you perform if you suspected chronic pancreatitis?

A

Faecal elastase-1 (produced by pancreas and passed into stool unaltered). Plain abdo X-ray. Ultrasound/CT. MRCP/ERCP.

46
Q

How do you manage chronic pancreatitis?

A

Remove precipitant (alcohol), pain control, treat diabetes, pancreatic enzyme supplements (Creon), vitamin supplementation, nerve plexus blocks, endoscopic stenting of strictures, surgery.

47
Q

What is cholestasis?

A

The impairment of bile formation/flow.

48
Q

What is primary sclerosing cholangitis?

A

Inflammatory/fibrotic process affecting intra/extrahepatic bile ducts. Leads to bile duct strictures. Aetiology unknonwn but 80% associated with IBD. Presents with pruritis, fatigue and jaundice. Leads to liver failure. Tx required.

49
Q

Which drug may cause malabsorption?

A

Orlistat: inhibits gastric and pancreatic lipase.

50
Q

How may small bowel bacterial overgrowth cause malabsorption?

A

Bacteria can deconjugate bile salts as well as metabolise B12.

GI and metabolism (25 decks)

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