Gastroenterology Flashcards
Features of Osmotic Diarrhoea + causes
Excess osmotically active particles in bowel.
Stops when fasted.
Causes: Laxatives (lactulose), malabsorption, damage to mucosa, motility disorder (eg hyperthyroid)
Features of Secretory Diarrhoea + causes
Bowel mucosa secretes excess water into the lumen.
Continues when fasted.
Causes: Cholera toxin, electrolyte transport disorders or congenital microvilli atrophy.
Features of Exudative diarrhoea
Alteration to membrane permeability and serum proteins –> blood and mucus into lumen, small stool amounts
Causes of Cholera + presentation
Vibrio Cholerae
Due to ingestion of contaminated food / water
Secretory diarrhoea - “rice water stools”
Presentation of laxative abuse
Weight loss and chronic diarrhoea
Colonoscopy - brown pigementation = melanosis coli due to lipofuscin
How does congenital glucose-galactose malabsorption cause diarrhoea?
Recessive –> dysfunction of SGLT1
Impaired uptake of glucose / galactose
Osmotic diarrhoea and life threatening dehydration
Infections that can cause acute liver failure
- <6 months: Sepsis, Hep B, Adenovirus, echovirus, Coxsackie B, HSV
- > 6 months: Hep A / B / E, EBV, Parvovirus B19
Mechanism of transmission Viral Hepatitis A - E
Hep A - Faecal-oral
Hep B - Perinatal / inoculation / sexual
Hep C - Vertical transmission, blood transfusion
Hep D - Depends on Hep B
Hep E - Contaminated water / pork
Viral Hepatitis treatment
Hep A - vaccinate contacts.
Hep B - Interferon, entecavir. Vaccine / IVIg if high risk
Hep C - PEG interferon, ribavarin
Serology acute Hep B infection
Positive: HbcAb IgM/ IgG, HbsAg, HBeAg
Negative: Anti-HBs, Anti-HBe
High HBV DNA titre
Serology Chronic Hep B infection
Positive: HbcAb IgG, HbsAg
Low DNA titre
Serology Hep B vaccination
Anti-Hbs only
Serology Cleared Hep B infection
Positive: HbcAb IgG, Anti-Hbs
Features of 2 types of food allergy
IgE mediated: Eg milk, nuts. Reaction within mins. 1st exposure –> sensitising event.
Non-IgE mediated: eg milk, coeliac. Delayed, N+V, food aversion, faltering growth
What is neonatal haemachromatosis?
Alloimmune disorder –> abnormal maternal Ab reaction to foetal liver
Accumulation of iron in liver
Dx: Iron storage outside the liver - salivary glands, pancreas, brain
Features of autoimmune liver disease
Rare in children. 3/4 female.
Genetic predisposition - HLA B8/DR3
AI - Activation of inflammatory response –> cytokine release –> macrophage activation –> hepatocellular lysis
AI response to parenchyma = AI hepatitis
AI response to biliary tree = Sclerosing Cholangitis
Anti-smooth muscle antibody
Tx: Steroids, DMARDs, ?transplant
Hepatotoxic drugs
Paracetamol
Sodium valproate
Indomethacin
NSAIDs
Abx
Anti-epileptics
Pathophysiology of Wilson’s Disease
Autosomal recessive - mutation to ATP7B
Reduced converstion apoceruloplasmin to ceruloplasmin
Oxidative damage to cells and accumulation in liver, kidneys, brain
Presentation: Neuro-psych, liver/renal failure
Investigation and treatment of Wilson’s Disease
Ix: Liver biopsy, pencillilamine challenge –> urinary copper, low serum ceruloplasmin and copper
Tx: Penicillamine / zinc acetate (copper chelator)
+/- liver transplant
Pathophysiology Alpha-1-antitrypsin deficiency
Autosomal recessive. Defect to SERPINA-1 gene.
Intracellular accumulation of misfolded A1A protein within the hepatocyte endoplasmic reticulum (ER), thus inhibiting its secretion.
Ultimately, this accumulation can result in liver cell injury and death. Increased risk of cancer.
Also lung tissue injury due to uninhibited neutrophil elastase
Presentation: Hepatitis and liver failure, lung disease
Investigation and management of alpha-1-antitypsin deficiency
Ix: Low plasma alpha-1-antitripsin
Tx: ?liver transplant
Features and treatment of fatty liver disease in children
Accumulation of fat in hepatocytes
Causes: Methotrexate, PCOS, Turner’s, obesity
Presentation: hepatomegaly and mildly deranged transaminases
Tx: Diet and exercise
Presentation hepatoblastoma
More <4y
Associations: FHx, Beckwith-Wiedemann, FAP, glycogen storage disorder
Palpable mass, abdo distention, weight loss, vomiting, jaundice
Raised alpha-fetoprotein
What is Gilbert’s syndrome and how does it present?
AR
Reduced bilirubin glucuronidation
Sx: Transient eps unconjugated jaundice
Most common site for intussusception
Small bowel - ileocaecal valve
What dose stool reducing substances test for?
Presence of malabsorption of lactose, fructose and galactose
What is short gut syndrome and what are the consequences?
Absence of large section of small intestine leading to malabsorption
1. Osmotic diarrhoea
2. Malabsorption –> faltering growth and bile salt depletion, depletion fat soluble vitamins
3. Steatorrhoea
4. Renal oxalate stones
5. Bile salt depletion –> gallstones
Which are fat soluble vitamins?
A
D
E
K
Effects of Vit B12 deficiency
Macrocytic anaemia
Demyelinating neuropathy
Pernicious anaemia = lack of intrinsic factors –> not able to absorb B12
Vitamin A deficiency presentation
Eyes - night blindness, dry, corneal opacification
Growth failure
Immune dysfunction
Thickened skin
Presentation of Vit E deficiency
Axonal degeneration
Progressive neuropathy
Retinopathy
Histology findings in coeliac disease
Crypt hypertrophy
Villous atrophy
Intra-epithelial lymphocytosis
Glandular hyperplasia
What genetic finding is associated with Coeliac disease?
HLA-DQ2/8
Serology in coeliac disease
IgA Anti-TTG
Low IgA
IgA EMA
Crohn’s histology
Skip lesions
Patchy erosions / ulcers
Fissures and fistulas
Increased lymphocytes
Transmural inflammation with multiple lymphoid aggregates and granulomas
Abnormalities ‘mouth to anus’
UC histology
MUCOSA MOST AFFECTED
Changes in colon only
Changed crypt architecture
Chronic inflammatory cells in lamina propria - lymphocytes and plasma cells
Treatment of IBD
1st line = 6-8 weeks exclusive flavoured polymeric formula diet
Steroids
Immunosuppression
What blood results are you likely to see in pyloric stenosis?
Low chloride
Low potassium
Low sodium
Metabolic alkalosis
Cow’s milk sensitive enteropathy histology in distal duodum
Patchy eneropathy
Mild disturbance of crypt villous architecture.
Raised mucosal lymphocyte and eosinophil
Eosinophilic oesophagitis treatment if severe
Oral elemental diet
Definition of GORD on pH studies
Probe in LO, monitors pH over 24 hours.
Reflux ep. pH <4 for at least 15 secs.
