Gastrointestinal > Malabsorption > Flashcards

Malabsorption Flashcards

(48 cards)

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1
Q

What is Maldigestion?

A

impaired breakdown of nutrients, luminal phase (eg pancreatic insufficiency)

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2
Q

What is Malabsorption?

A

defective mucosal uptake and transport of adequately digested nutrients. Selective or global.

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3
Q

What is Malassimilation?

A

Encompasses maldigestion and malabsorption

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4
Q

What are the three processes of the luminal phase of absorption?

A
  • Nutrient hydrolysis
  • Fat solubilisation
  • Lumenal availability
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5
Q

Describe nutrient hydrolysis

A
  • Enzyme deficiency: pancreatic insufficiency
  • Enzyme inactivation: ZE syndrome
  • Inadequacy of mixing: rapid transit, surgical resection
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6
Q

Describe fat solubilisation

A
  • Decreased bile salts: cholestasis, cirrhosis
  • Bile salt deconjugation: bacterial overgrowth
  • Bile salt loss: ileal disease or resection
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7
Q

Describe lumenal availability

A
  • Bacterial consumption of nutrients (bacterial overgrowth): B12 deficiency
  • Decreased intrinsic factor (pernicious anaemia): B12 deficiency
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8
Q

What are the processes of the mucosal phase of absorption?

A
  • Brush border hydrolysis

- Epithelial transport

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9
Q

Describe brush border hydrolysis

A

lactase deficiency (post gastroenteritis, alcohol, radiation)

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10
Q

Describe epithelial transport

A
  • Reduced absorptive surface - resection
  • Damaged absorptive surface – coeliac disease, tropical sprue, Crohn’s disease, ischaemia
  • Infections – Giardia, SIBO
  • Infiltration – lymphoma, amyloid
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11
Q

Describe the post-mucosal phase of absorption

A

Post-absorptive processing – lymphatic obstruction (lymphangectasia, neoplastic, TB)

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12
Q

What are the clinical features of malabsorption?

A
  • Diarrhoea and weight loss despite adequate intake
  • Bloating, distention, cramps, borborygmi (bowel sounds)
  • Lethargy, malaise
  • Symptoms often mild, non-specific
  • Malabsorption can be global, or specific nutrients
  • Malabsorption syndrome (steatorrhoea, distention, weight loss, oedema) is a RARE presentation
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13
Q

What are the clues in the history?

A
  • Weight loss
  • Diarrhea/Steatorrhoea (fat, bile salts)
  • Abdominal distension/gas (carbohydrate)= lactose intolerance
  • Intestinal “angina” (vasculopathy, impaired circulation to intestine so mesenteric ischaemia)
  • Metabolic bone disease (calcium and B12)
  • GI surgery
  • Pancreatitis
  • Cystic fibrosis
  • Alcohol
  • FHx coeliac
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14
Q

What is the evidence of malnutrition in the skin?

A
  • angular cheilitis (cracking of skin), glossitis
  • dermatitis herpetiformis
  • oedema
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15
Q

What is the evidence of malnutrition neurologically (B12)?

A
  • Peripheral neuropathy
  • Ataxia (posterior column)
  • Psychosis, dementia
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16
Q

How can laboratory results indicate malnutrition?

A
  • Microcytosis: iron deficiency (common in coeliac, otherwise suspect GI blood loss)
  • Macrocytosis (RBC too big): B12, folate deficiency, but also common in coeliac, alcohol
  • Elevated ALP +/- low Ca
  • Hypoalbuminaemia (protein malabsorption)
  • Evidence of multiple nutritional deficiencies
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17
Q

What are the main causes of malabsorption?

A
  • Coeliac disease
  • Pancreatic insufficiency
  • Small bowel overgrowth (SIBO)
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18
Q

What are the other causes of malabsorption?

A 
Pernicious anaemia (B12)
Bile acid malabsorption (BAM)
Intestinal resection
Vascular insufficiency
Crohn’s disease
Lactase deficiency
Cholestasis
Giardiasis
Lymphoma
Lymphatic obstruction
TB
Tropical sprue
Whipple’s disease
Zollinger Ellison syndrome
Amyloid
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19
Q

Describe diagnostic testing for malabsorption

A

-Testing for malabsorption (eg faecal fat, D-xylose test) rarely used / available
-Unless strong pointers to one cause, investigate non-invasively for the 3 commonest causes first
=Tissue Transglutaminase (TTG) – Coeliac disease
=Faecal elastase – Pancreatic insufficiency
=Glucose H2 breath test - SIBO
-Then if clinically suspected move on to more targeted investigation

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20
Q

What other investigations are there for malabsorption?

Study These Flashcards
A
  • Stool microbiology (Giardia)
  • Faecal calprotectin (Crohn’s)
  • 7alpha-cholestenone or SeHCAT test (Bile acid malabsorption)
  • Lactose H2 breath test
  • Small intestinal biopsy (coeliac, Giardia, Crohn’s, Whipples, tropical sprue, lymphangectasia, lymphoma)
  • Small bowel imaging (BaFT, MRI, Capsule)
  • CT/CT angiogram (pancreatic disease, mesenteric ischaemia
21
Q

What is Coeliac Disease?

Study These Flashcards
A 
Small bowel disorder characterized by:
-mucosal inflammation 
-villous atrophy 
-crypt hyperplasia 
which occur upon exposure to dietary gluten and which demonstrate improvement after withdrawal of gluten from the diet.
22
Q

What are the possible causes of coeliac disease?

Study These Flashcards
A

-Genetic predisposition – HLA DQ2, DQ8 (25% population vulnerable)
-Exposure to gluten (gliaden) in wheat, barley, rye
-Gliaden-reactive T lymphocytes
-Tissue transglutaminase antibodies
=Enteropathy
=Prevalence up to 1/100
=Many subclinical or asymptomatic

  • Clinically overt
  • Undiagnosed, silent
  • Latent (potential)
23
Q

What are the clinical symptoms of coeliac disease?

Study These Flashcards
A
  • Diarrhoea
  • Anaemia
  • Dyspepsia
  • Abd pain, bloating
  • Weight loss
  • Mouth ulcers
  • Fatigue
  • Neuropsychiatric symptoms
24
Q

What is the classic presentation of coeliac disease (historical)?

Study These Flashcards
A
  • Childhood
  • FTT / Weight loss
  • Short stature
  • Malnutrition
  • Steatorrhoea
  • Delayed puberty
  • Osteomalacia
  • Myopathy
25
What are the clues on investigation for coeliac disease?
- Anaemia (microcytic, macrocytic) - Iron, folate deficiency - Macrocytosis without anaemia - Hyposplenic blood film - Low calcium, elevated Alk Phos - Raised transaminases - Hypoalbuminaemia
26
What other disease is coeliac disease associated with?
``` Osteoporosis Infertility Dermatitis herpetiformis Lymphocytic colitis Ulcerative jejunitis Lymphoma Type1 Diabetes Thyroid disease Autoimmune liver disease Sjogren’s syndrome Down’s syndrome Cerebellar ataxia Other malignancies ```
27
Describe diagnosis of coeliac disease
Serological markers -Anti-tissue transglutaminase antibody (IgA) (TTG) Sensitivity and specificity >95% =Anti-endomysial antibody (IgA) =Anti-gliadin antibody (IgA, IgG) Small intestinal biopsy
28
What endoscopic changes can be seen in coeliac disease?
- Scalloping - Loss of Kerkring's folds - Mosaic pattern
29
What is the treatment for coeliac disease?
- Gluten free diet (life-long) - Dietician - Nutritional supplements - Screen for complications – bone disease - Very rarely, need for immunosuppressant medication for refractory cases
30
Describe Pancreatic exocrine insufficiency (PEI)
- Pancreas produces 1.5L/day of bicarbonate and enzyme-rich fluid - Enzymes for digestion of fat, protein, CHO - Lipolytic activity declines first so fat absorption mainly affected - Overt clinical consequences unlikely unless 90% of function lost - Steatorrhoea, weight loss, vitamin deficiency (A,D,E,K), also more minor symptoms
31
What are the causes of PEI?
- Chronic pancreatitis - Pancreatic cancer - Cystic fibrosis (obstruction) - Haemochromatosis - Pancreatic resection - Gastric resection
32
What are the causes of chronic pancreatitis?
- Alcohol – 80% present with pain - Duct obstruction – tumours, stones - Cystic fibrosis, other genetic causes - Systemic disease eg SLE= atrophy - Autoimmune (IgG4) pancreatitis
33
Describe cystic fibrosis
- Autosomal recessive, CFTR gene - Impairment in bicarbonate and chloride secretion – thick sticky mucus - Pancreatic involvement most common GI problem, esp in more severe genotypes - 85% affected, starts v early. - Commonly leads to PEI in childhood
34
How is PEI diagnosed?
-Risk factors (alcohol, CF) -Symptoms -Pancreatic imaging (CT, MRI) -Tests of exocrine pancreatic function =Direct – eg Secretin stimulation tests (sensitive but cumbersome) =Indirect – eg Faecal elastase, Pancreolauryl (only reliably detect moderate to severe PEI)
35
What is the treatment for PEI?
- Pancreatic enzyme replacement - Taken with meals and snacks - Gastric acid suppression - Vitamin supplements
36
Describe Small Intestinal bacterial overgrowth (SIBO)
- Normally 105 to 109 bacteria/ml present in distal small bowel - Colon has up to 1012 bacteria/ml - Mostly Gram- aerobic bacteria in ileum, Gram+ anaerobic bacteria in colon - In bacterial overgrowth this balance is lost - Increasingly recognised as a feature in other conditions – liver disease, IBS, obesity, CF, coeliac disease - Overestimated how many patient have this
37
What are the causes of bacterial overgrowth?
-Stasis -- Strictures =Crohn’s disease =Tuberculosis --Hypomotility =Old age =Opiate analgesics =Diabetes =Systemic sclerosis -Blind loops, Diverticulae -Immunodeficiency -?Obesity
38
What are blind loops?
- Stagnant loop out of continuity with gut so growth - Billroth 2 partial gastrectomy - Gastric bypass
39
What are the consequences of bacterial overgrowth?
- Vitamin B12 malabsorption - Bile acid deconjugation - Intraluminal protein utilization - Brush border damage - Ulceration of mucosa - Bowel dysmotility
40
Describe diagnosis of SIBO
- Quantitative culture of jejunal fluid is the gold standard (> 105/mL is abnormal) - Glucose/Hydrogen breath test more practical (not accurate) - Small bowel radiology to look for anatomical abnormalities
41
What is the treatment for SIBO?
- Treatment with 2 weeks of antibiotics e.g. tetracycline, ciprofloxacin, rifaximin - Often needs repeat treatment
42
Describe Bile Acid Malabsorption (BAM)
- Bile acids specifically absorbed in ileum - Cause secretory diarrhoea in colon - Affected by ileal disease or resection - Also impaired in post- cholecystectomy, rapid transit and other malabsorptive states - Primary BAM may reflect over-production rather than malabsorption (receptors defective)
43
What are the types of bile acid malabsorption?
``` -Type 1 =Ileal disease or resection -Type 2 =Idiopathic -Type 3 =Assoc with cholecystectomy, rapid transit, coeliac, SIBO, chronic pancreatitis ```
44
What is used to investigate BAM?
Serum 7-alpha cholestenone | SeHCAT retention
45
What is the treatment for BAM?
Cholestyramine | Colesevelam
46
Describe Giardia lamblia
-Non-invasive pathogen -Malabsorption due to multiple factors =Brush border damage =Reduction in absorptive surface =Bile acid utilization =Induction of hypermotility =Enterotoxin -Treatment of choice is metronidazole
47
Which other parasites cause malabsorption?
``` -Protozoa =Isospora belli =Cryptosporidium =Microsporidia (Enterocytozoon bieneusi) -Tapeworms (blood loss and iron deficiency) =Taenia saginata (beef tapeworm) =Hymenolepis nana (dwarf tapeworm) =Diphyllobothrium latum (fish tapeworm) -Nematodes =Strongyloides =Capilliarasis ```
48
Describe Whipple's disease
- Uncommon bacterial infection in older men - Caused by Tropheryma whippleii - Presents with diarrhoea, arthritis, fever, cough, headache, muscle weakness - Intestinal mucosa is infiltrated by foamy macrophages containing PAS-positive material - Antibiotic therapy for months to years.
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