Gastroenterology Flashcards

1
Q

What substances are transported by SGLT1?

A

Galactose Glucose H2O Na

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2
Q

What transporter uptakes fructose in the small intestine?

A

GLUT 5 (Way to remember 5 starts with an F)

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3
Q

Describe the chloride secretory process in the small intestine

A

Chloride can be secreted actively throughout the small + large intestine Enters the intestinal lumen from the blood by the Na/K/2Cl co transporter Intracellular mediators of secretion (cAMP, cGMP, Ca) open apical Cl- channels (CFTR) Ca activated Cl- channels + basolateral K+ channels

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4
Q

Where are bile salts absorbed?

A

Terminal ileum

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5
Q

Where is calcium absorded?

A

Maximally absorbed in the duodenum + proximal jejunum

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6
Q

Where is B12 absorbed?

A

Terminal ileum

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7
Q

What is predominantly absorbed in the terminal ileum?

A

The 2 B’s Bile salts/ acids B12

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8
Q

What location are medium chain triglycerides directly absorbed into?

A

Portal circulation

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9
Q

Where is zinc primarily absorbed?

A

Jejunum

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10
Q

Where is iron absorbed?

A

Duodenum / proximal jejunum

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11
Q

Where is folic acid primarily absorbed?

A

Duodenum

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12
Q

What is the difference between fatty acid globules + fatty acid crystals?

A

Fatty acid globules indicate presence of triglycerides = liver disease OR lipase deficiency (CF, cholestasis, pancreatic disease). - Suggests fats are unable to be broken down - Further investigations = sweat test for CF, assess degree of malabsorption (e.g. 3 day faecel study, breath test), LFT’s Fatty acid crystals indicate presence of FFA (free fatty acids) = mucosal damage = malabsorption (e.g. coeliac disease, short gut) - Suggests fat broken down but not absorbed

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13
Q

Would you expect stool alpha 1 anti-trypsin to be reduced or elevated in lymphangiestasia?

A

Elevated

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14
Q

True or false T21 is associated with an increased risk of coeliac disease

A

True! 5-16 fold increase compared with the general population

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15
Q

Definition of coeliac disease

A

T cell auto-immune mediated malabsorptive disorder characterised by a permanent gluten sensitive enteropathy resulting in malabsorption, FTT + GIT symptoms Gliadin is the toxic component of gluten in coeliac disease

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16
Q

Incidence, prevalence + age of onset of coeliac disease

A

Incidence= 20 / 100 000 Prevalence = 1/1000 Age of onset = usually develops before 2yrs

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17
Q

Risk factors for coeliac disease

A

Family history - 1st degree relative 5-7.5% affected - 2nd degree relative 2-3% affected Food: BROW (barley, rye, oats, wheat) Female Infection with adenovirus type 12 Immunologic - Strongest association with HLA DQ2 + DQ8 - 90-95% express HLADQ2, 5-10% carries HLA DQ8 - 40% of the white population +’ve f Autoimmune conditions - T1DM - Autoimmune thyroid / hepatitis/ cholangitis - Addison - Sjogren - Rheumatoid arthritis - Primary biliary cholangitis Conditions -T21 - Williams - IgA deficiency - Turner’s

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18
Q

What are common extra-intestinal manifestations of coeliac disease?

A

Chronic fatigue Iron deficiency (usually unresponsive to iron supplements) Osteoporosis Short stature Delayed puberty Arthritis / arthralgia Epilepsy Peripheral neuropathies Dental enamel hypoplasia Apthous stomatitis Dermatitis herpetiformis

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19
Q

When is coeliac testing recommended?

A

•Persistent unexplained abdominal or gastrointestinal symptoms • Faltering growth • Prolonged fatigue • Unexpected weight loss • Severe or persistent mouth ulcers • Unexplained iron, vitamin B12, or folate deficiency • Type 1 diabetes • Autoimmune thyroid disease • Irritable bowel syndrome • First degree relatives of people with coeliac disease • Dermatitis herpetiformis

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20
Q

What are the tests for the diagnosis of coeliac disease?

A

Initial approach - Anti TG2 IgA antibodies (declines if the patient is on a gluten free diet) - Total IgA serum (to exclude IgA deficiency) - If selective IgA deficiency present test IgG antibodies to TG2 HLA status (strongest association with HLA DQ2 + DQ8) Duodenal histology

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21
Q

Where should a biopsy be taken from to diagnose coeliac disease?

A

Descending part of the duodenum / duodenal bulb

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22
Q

Histological features of coeliac disease on biopsy?

A
  • Increased intraepitheral lymphocytes - Flat mucosa with total mucosal atrophy - Crypt hyperplasia - Epithelial apoptosis - Mucous membrane inflammation
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23
Q

What are the different test for coeliac disease?

A

Sensitivity (percent) Specificity (percent) Tissue transglutaminase; tTG (IgA, human)[1-3] 90 to 100 95 to 100 1st line Anti-endomysial antibody (IgA)[1] EMA 93 to 100 98 to 100 As accurate as tTG IGA but more expensice + operator dependent Deamidated gliadin peptide; DGP (IgA)*[4] 80 to 91 91 to 95 Particularly sensitive in kids <2yrs Deamidated gliadin peptide; DGP (IgG)*[4] 88 to 95 86 to 98 Particularly sensitive in kids <2yrs NO LONGER RECOMMENDED ROUTINELY Anti-gliadin antibody IgA[1] 52 to 100 72 to 100 Anti-gliadin antibody IgG[1] 83 to 100 47 to 94

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24
Q

What types of cancers is coeliac disease associated with?

A

20 x risk of small bowel lymphoma 30 x risk of small bowel adenocarcinoma 2-4 x risk of oesophageal cancer

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25
Q

What does sucrose break up into?

A

Glucose + fructose Enzyme: sucrase isomaltase

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26
Q

What does maltose break up into?

A

Glucose + glucose Enzyme: sucrase isomaltase

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27
Q

What does lactose break down into?

A

Glucose + galactose Enzyme: lactase

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28
Q

Cow’s milk protein allergy vs. cow’s milk protein intolerance

A

Cow’s milk protein allergy - IgE mediated immunological reaction to cow’s milk protein Cow’s milk protein intolerance - Non immunologic reaction - Most common = lactase deficiency

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29
Q

I am a six month old female, fully breast feed and present with 2 months of diarrhoea + rash as shown with sparse scalp hair but I am NOT failing to thrive.

What do I have?

A

Acrodermatitis enteropathica

  • Autosomal recessive
  • Inability to absorb zinc = zinc deficiency
  • Features
    • Cutaneous eruption = vesiculobullous, eczematous, dry, scaly, or psoriasiform skin lesions symmetrically distributed in the perioral, acral, and perineal areas
    • Hair = reddish tint + alopecia
    • Occular = photophobia, conjunctivits, blepharitis + corneal dystrophy
    • Chronic diarrhoea, stomatitis, glossitis, paronychia, irritability, delayed wound healing, infections (including superinfection with Candida albicans)
  • Treatment
    • Zinc supplementation
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30
Q
A
  • Dilated lymphatics shown
  • Stool alpha 1 anti-trypsin will be increased
  • Lymphangiectasia
  • Diffuse or localised ectasia of enteric lymphatics
  • Associations: Turner’s, Noonan’s, Klippel-Trenaunay
  • Clinical manifestastions: intermittent diarrhoea, N+V, steatorrhoea, chylothorax + chylous ascited, pleural effusions + ascites
  • Treatment:
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31
Q

A six-year-old boy with Down syndrome presents to your practice with persistent diarrhoea for the past four weeks. Stool microscopy reveals the following findings: Fat globules: +; Fatty acid crystals: +++; Red blood cells: 0; White blood cells: 0; Faecal pH: 5.5 [> 6.5]; Reducing sugars: 1% [< 0.25%]. What is the most likely diagnosis?

a) coeliac disease.
b) cow’s milk enteropathy.
c) crohn disease.
d) infectious colitis.
e) lactose intolerance.

A

Predominant feature is fatty acid crystals.

Fat globules = intraluminal problem eg. failure of enzyme process or bile to suspend fats = maldigestion

Fatty acid crystals = mucosal/brush border problem (fatty acid not absorbed) = malabsorption

The presence of reducing substances suggests carbohydrate malabsorption.

Acidic stool (low pH) suggests osmotic diarrhoea, of which one of the major causes is malabsorption.

There is no evidence of inflammation (no white or red blood cells).

A: Coeliac disease is the most likely diagnosis. It should be noted that the incidence of Coeliac disease is increased in patients with Down syndrome.

B: Infants with food protein-induced enteropathy have malabsorption, failure to thrive, anaemia, diarrhoea, vomiting, and hypoproteinemia, which usually is induced by cow’s milk protein. It is most likely to occur in infants fed intact cow’s milk prior to nine months of age. The disorder generally resolves spontaneously after two years of age.

C: Crohn’s disease – no evidence of inflammation in the stool.

D: Infectious colitis – again, no evidence of inflammation in the stool.

E: Lactose intolerance – while you would get reducing substances and low pH, there should be no features of fat malabsorption.

The correct answer is A.

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32
Q

Differentiating features of Crohn’s + UC

A

Crohns

  • Panenteric (gum to bum)
  • Patchy
  • Transmural
  • Granulomas

Ulcerative Colitis

  • Colonic
  • Confluent
  • Mucosal* May be transmural in acute severe UC*
  • NO granulomas
33
Q

What infections can mimic colitis?

A
  • Salmonella
  • Shigella
  • Yersinia
  • Campylobacter
  • C.Diff
  • E.Coli
  • Entamoeba histolytica
34
Q

What infections can mimic ileitis?

A
  • Tuberculosis
  • Yersinia
35
Q

What is the link between appendicectomy + IBD?

A
  • Early appendicectomy reduces the risk of IBD
36
Q

What extra-intestinal manifestations correlate with disease activity?

A
  • Peripheral arthritis
  • Erythema nodosum
  • Anaemia
37
Q

What extra-intestinal features are MORE common in Crohn’s disease?

A
  • Oral apthous ulcers
  • Fevers
  • Erythema nodosum
  • Digital clubbing
  • Arthritis
38
Q

What extraintestinal features are MORE common in ulcerative colitis?

A
  • Pyoderma gangrenosum
  • Sclerosing cholangitis
  • Chronic active hepatitis
  • Ankylysing spondylitis
39
Q

What is the MOST common extraintestinal manifestation in IBD and what are the subtypes?

A

Arthritis

Peripheral arthritis

Types 1

  • Pauciarticular, asymmetrical, large joints
  • Mirrors disease activity
  • HLAB27, HLAB35 HLA DR related

Type 2

  • Polyarticular, small joints
  • Independent of gut disease activity
  • May be associated with uveitis

Axial arthritis

  • Independent of gut disease activity
40
Q

What is calprotectin?

A

Neutrophil derived inflammatory marker

Highly sensitive but NON-SPECIFIC

If ESR, calprotectin normal then IBD VERY unlikely

41
Q

Endoscopic features of Crohn’s

A
42
Q

Endoscopic features of ulcerative colitis

A
43
Q

What are the histology features in UC?

A
  • Heavy inflammation in the mucosa
  • Loss of normal epithelial cells
  • Crypt abscess
  • Cryptitis
  • Nothing going on in the submucosal area
44
Q

What are the histology features in Crohns?

A
  • Fissures
  • Submucosal infiltrates
  • Granulomas
45
Q

What disorders are associated with monogenic IBD ‘aka very early onset IBD’

A
  • Disorders of regulatory T cell + IL10 function
    • IL10 mutation
  • Disorders of neutrophil function:
    • CGD, GSD 1B
  • Disorders of epithelial barrier function
    • NEMO defect
  • Hyper + auto-inflamm defects
    • XIAP, Hermansky-Pudak
  • Complex disorders of T + B cell function
    • Wiskott Aldrich, Omenn
  • Disorders of Ig function
46
Q
A
47
Q

What is the definition of very early onset IBD?

A

<6yrs at diagnosis

Requires extensive work up for monogenic disorders

  • Neutrophil function tests
  • Gene panel
  • Lymphocyte subsets
  • Functional antibodies to vaccines
  • Immunoglobulins
48
Q

What is the best predictive factor of prognosis in UC?

A
  • Severity at diagnosis
  • 70% remission by 2 months
  • 30% colectomy by 5 years
  • Long term cancer risk especially: pancolitis, associated sclerosing cholangitis
49
Q

Is toxic megacolon more common in UC or Crohns?

A

UC

50
Q

What are the diagnostic criteria for toxic megacolon?

A
  • Radiographic evidence of colonic distension
  • At least 3 of the following
    • Fever
    • HR
    • Neutrophilic leukocytosis
    • Anaemia
  • In addition to the above at least 1:
    • Dehydration
    • Altered level of consciousness
    • Electrolyte disturbance
    • Hypotension
51
Q

Who is at increased risk of developing coeliac disease?

A
  • First degree relatives 10%
  • Type 1 diabetes 3-12%
  • T21 5-12%
  • Autoimmune thyroid disease
  • Turners
  • Williams syndrome
  • IgA deficiency
  • Autoimmune liver disease
52
Q

Which one of the following autoantibodies is MOST specific for coeliac disease?

  • IgA endomysial
  • IgA gliadin
  • IgA gluten
  • IgA reticulin
  • IgG gluten
A

IgA endomysial

53
Q

What causes false positives with a fecal calprotectin test?

A
  • NSAID use
  • After a chest infection
  • After bleeding into the bowel
54
Q

Does fecal calprotectin levels correlate with clinical disease activity in IBD?

A

Yes!

55
Q

What is the significance of HLA DQ2/8 typing in coeliac disease?

A
  • HLAD2/D8 genotypes are found in at least 98% of patient with coeliac disease
    • HLA DQ2 (90-95%)
    • HLA DQ8 5-10%
  • BUT 30-40% of normal population have HLADQ2/8
  • Negative is useful- excludes coeliac
  • Positive not very useful!
56
Q

Are symptoms required for a diagnosis of coeliac disease?

A

No!

5-10% of patients will be asymptomatic

57
Q

What can cause a FALSE positive TTG test?

A
  • T1DM
  • Chronic liver diease
  • Psoriatic/ reactive arthritis
  • Heart failure
58
Q

What is Kwashiorkor?

A
  • Insufficient intake of protein and / or calories
  • Apathetic child who refuses to eat
  • Thinning of hair + skin
  • Soft, pitting, painless oedema, usually involving feet + legs
59
Q

What is marasmus?

A
  • Severe calorie malnutrition
  • “Wizened old man”
  • Hypothermia, bradycardia + hypotension
60
Q

What are the adverse effects of PPI’s?

A
  • Respiratory infections
  • C.diff infections
  • Bone fractures
  • Hypomagnesaemia
  • Low B12
  • Tubulointerstitial nephritis
  • Polyps
61
Q

What is the definition of diarrhoea?

A
  • Increase in FREQUENCY, VOLUME or FLUIDITIY of stool
  • WHO= 3 x loose water stools in 24hrs
  • Stoole volume > 10mL/kg/day
62
Q

What are the features of OSMOTIC diarrhoea?

A
  • Caused by non-absorbed nutrients in the intestinal lumen dragging water + into the gut (therefore gut HYPEROSMOLAR to blood)
  • Ceases when oral intake ceases
  • Volume <200mL/day
  • Na < 70meq/L
  • Osmotic gap HIGH >50mOsml/kg
  • Reducing substances present
  • pH <5 therefore can cause excoriation
  • Causes;
    • Osmotic laxatives
    • Mucosal injury: infective, inflammation (IBD), immune (celiac), vascular
    • Disaccharidase deficiency
    • Transport overload (increases sugar/fruit)
    • Bacterial overgrowth
63
Q

What are the features of secretory diarrhoea?

A
  • Drags water out into the gut with SODIUM (due to reduced absorption of electrolytes or abnormal ion transport into intestinal epithelial cells)
  • CONTINUES when oral intake ceases
  • Volume >200mL/day
  • Na > 70meq/L
  • Osmotic gap LOW <50mOsml/kg
  • Reducing substances ABSENT
  • pH >6
  • Causes;
    • Congenital transport + mucosal defects (microvillus inclusion MYO5B), tufting enteropathy (EPCAM)
    • Secretagogue: toxigenic, bile acid malabsorption
    • Tumours
    • Short gut
    • Rapid transport
64
Q

What is the 1st + 2nd most common trigger of eosinophilic oesophagitis?

A
  • MOST common = milk
  • 2ns most common = egg
65
Q

What is the inheritance + gene associated with Wilson’s disease?

A
  • Autosomal recessive
  • ATP7B gene
66
Q

What is the pathophysiology of Wilson’s?

A
  • Deficiency in ATP7B gene
    • Decrease in copper transport into bile
    • Impairs incorporation of copper into ceruloplasmin
    • Inhibits ceruloplasmin secretion into blood
  • Copper accumulates in the liver –> production of ROS –> cirrhosis
  • Non ceroplasmin bound copper spills from the liver into the circulation + accumulates in other organs
67
Q

What are the findings in Wilson’s disease for:

  • Ceruloplasmin levels
  • Serum copper levels
  • Urinary copper levels
  • Kayser Feischer rings
  • Genetic screening
  • Liver enzymes
A
  • Ceruloplasmin levels: REDUCED
  • Serum copper levels: high, low or normal
  • Urinary copper levels: ELEVATED
  • Kayser Feischer rings: may not be present in young children
    • Need slit lamp to visualise
    • Resolves with treatment
  • Genetic screening: ATP7B gene mutation
  • Liver enzymes
    • Low ALP is common
    • High AST:ALT ratio (4:1)
68
Q

What is the treatment of Wilson’s?

A
  • Dietary restriction: liver, shellfish, nuts, chocolate
  • Copper chelating agents
    • Penicillamine: 10-15% of patient have worsening of neurological condition + it can cause Goodpastures, SLE + polymyositis
    • Triethylene tetramine dihydrochloride (trientine)
    • Ammonium tetrhiomolybdate
  • Adjuvant therapy
    • Zinc: impairs gastrointestinal absorption of copper
  • Liver transplant
69
Q

TRUE or FALSE pruritis in jaundiced infants is due to retained bilirubin in the skin?

A

False! It is due to retained bile ACIDS

70
Q

TRUE or FALSE alpha 1 antitrypsin deficiency can be ruled out if the A1AT level is normal

A

FALSE! A1AT is an acute phase reactant therefore it can be falsely high. Need to do a phenotype instead to rule out A1AT deficiency.

71
Q

What is SPINK1 gene mutation associated with?

A

Hereditary pancreatitis

72
Q

What is the inheritance of Alagille syndrome?

A

Autosomal DOMINANT

73
Q

What are the major + minor features in Alagille syndrome?

A

MAJOR

  • Right sided heart lesions (TOF, pulmonary atresia, VSD, ASD)+ aortic coarctation
    • Peripheral pulmonary stenosis = MOST common
  • Posterior embryotoxin
  • Vertebral anomalies
    • Butterfly or hemi-vertebrae
  • Cholestasis with paucity of bile ducts

MINOR

  • Short stature
  • Delayed puberty
  • High pitched voice
  • Renal anomalies
  • Short radii
  • Hypercholesterolaemia
  • Vascular anomalies
74
Q

What is more common in childhood hepatoblastoma of hepatocellular carcinoma?

A

Hepatoblastoma

75
Q

What conditions are associated with hepatoblastoma?

A
  • Beckwith-Wiedermann
  • Preterm infants
  • IUGR/ low birth weight
  • FAP
  • Congenital retinal pigmentation
  • Hemihyperplasia
  • Aicardia syndrome
  • T18
76
Q

What is the MOST common benign liver tumour in childhood?

A

Hepatic haemangioma

Can cause hypothyroidism as receptors on the tumour can inactivate T4

77
Q

TRUE or FALSE in acute liver failure, blood ammonia level correlates with the severity of encephalopathy

A

Ammonia may indicate encephalopathy is present but does not correlate with severity. Ammonia may also suggest a urea cycle defect of organic acidaemia.

78
Q

TRUE or FALSE a soy based lipid emulsion should be added to TPN when liver derangement is present to prevent further deterioration in liver enzymes

A

FALSE. Soy based lipids (intralipid) are PROINFLAMMATORY and no longer used. Fish oil based lipids (SMOF) are used as they more liver friendly.