Gastroenterology Flashcards
What is the genetic basis of Menke Kinky Hair disease?
- X-linked recessive gene on chr. Xq13.
- Causes defect in copper transport.
What are the clinical features of Menke Kinky Hair disease?
- Progressive neurodegeneration and severe mental retardation.
- Seizures, hypotonia, feeding difficulties, optic atrophy.
- Colourless hair, kinky and fragile.
- Chubby red cheeks.
- Death <3 years.
What are investigations for Mankes Kinky Hair diasease?
- Hair shaft examination: trichorrhexis nodosa (fractures along hair shaft), pili torti (twisted hair), monilethrix (brittle hair)
- Serum copper (reduced), caeruloplasmin (reduced).
How is cows milk protein allergy related to GOR?
- Allergy causes inflammation and consequent dysmotility.
- GOR attributable to CMPA in 16-42%.
- Study 41% had CMPA and responded to MC elimination (with challenge).
- Associated diarrhoea and atopic dermatitis.
What is the most important pathophysiological basis of gastroesophageal reflux?
- Transient relaxation of the lower oesophageal sphincter.
What is the pathogenesis of eosiniphilic oesophagitis?
- T-helper type 2 cytoine mediated pathway activation.
- Leads to production of eotaxin 3 (powerful eosinophil chemo-attractant) by oesophageal endothelium.
How do PPI’s work to improve eosinophilic oesophagitis?
- PPI inhibition of eotaxin 3 secretion.
What are the expected insensible water losses in a 26w 750g infant?
- Very immature prem infants (<1kg) may lose 2-3ml/kg/h due to immature skin, lack of subcutaneous tissue and large exposed surface area.
- Larger prem infants (2-2.5kg) have insensible water loss of 0.6-0.7ml/kg/h.
What are the features of Cowden Syndrome?
- Autosomal dominant.
- 80% have PTEN mutation.
- Facial trichilemmomas (often perioral), acral keratosis, papillomatous papules.
- GI hamartomas and oesophageal glycogenic acanthosis are minor criteria only but are present in 80%.
- Other associtions - breast fibroadenomas, breast cancers, goitres and thy roid cancers.
- Macrocephaly, genitourinary cancers including renal cell carcinoma and intellectual disability.
Features of Hepatitis A infection?
- Highly contagious.
- Transmitted via faecal-oral route.
- Typical incubation period 3/52.
- Symptoms vary from anicteric with gastroenteritis symptoms to high fever and jaundice lasting up to 2 weeks.
- Lymphadenopathy and splenomegaly may be present.
- Diagnosis: Hepatitis A IgM positive - stool and blood PCR are available.
- Complications are uncommon but include pancreatitis, acute liver failure and prolonged cholestatic syndrome with fat malabsorption lasting many months.
- Treatment supportive and prognosis generally excellent.
Features of Non-alcoholic statohepatitis?
- Common cause of deranged LFTs in obese children.
- USS and LFTs assist in diagnosis though neither is specific or sensitive - differentials dhould be excluded.
- Investigate for manifestations of metabolic syndrome.
- Mainstay of treatment is diet and lifestyle modification.
- Metformin and Vit E being used with mixed results.
Features of Type 1 autoimmune hepatitis?
- Fulminant hepatitis affects around 3% with type 1 autoimmune hepatitis.
- Charachterised by hepatic encephalopathy, coagulopathy and jaundice.
- Teenagers affected.
- ANA and anti-SMA positive.
At what level is a swallowed foreign body most likely to become impacted?
- Oesophagus at the level of cricoid.
What is the pathogenesis of FPIES?
- Food allergens cause local inflammation, increased intestinal permeability and fluid shifts.
- T cell mediated.
- Increased TNFa and decreased TNFb.
In FPIES which food is least likely to show resolution by 3y?
- Rice (40%)
- Cows milk (60-90%)
- Soy (25-90%
- Vegetables (67%)
- Oats (66%)
What carbohydrates are transported by intestinal sodium-glucose transporter 1 (SGLT-1)?
- Glucose and galactose.
What are the required kCal/gram of glucose, protein and lipid for a pareneterally fed neonate?
- Glucose and protein 4 Kcal/gram.
- Lipid 9 Kcal/gram.
What are the criteria for osmotic diarrhoea?
- Na <70mEq/L
- Osmolality >(Na+K)x2
- pH <5
- Reducing substances.
- Volume >200ml/d.
- Ceases when oral intake stops.
What are the criteria for secretory diarrhoea?
- Na >70mEq/L
- Osmolality = (Na+K)x2
- pH >6
- No reducing substances.
- Volume >200ml/d
What do fatty acid crystals in stool indicate?
- Absorptive fat malabsorption.
What do fat globules in stool indicate?
- Digestive fat malabsorption.
What changes do you see on blood test in bacterial small bowel overgrowth?
- Decreased B12 - increased bacterial consumption.
- Increased folate - enhanced folate synthesis.
How is fructose absorbed?
- Often bound to glucose to form disaccharide sucrose.
- Free fructose absorbed directly by the intestine.
- When fructose consumed in the form of sucrose it is digested and absorbed as free fructose.
- Sucrose comes in contact with the membrane of the small intestine and the enzyme sucrase catalyses cleavage to yield 1 glucose and 1 fructose.
- Fructose absorption occurs on the mucosal membrane via facilitated transport involving GLUT5 (Na+ independent facilitated diffusion) and leaves via GLUT2.
Which immunological mechanism is the major cause of destruction of small intestinal villous architecture in coeliac disease?
- Gluten peptides (gliadin), penetrate between the intestinal epithelial cells.
- In the lamina propria they are deamidated by free tissue transgutaminase.
- This is taken up by macrophages and presents on HLA-DQ2 or DQ8 which activates cytotoxic T cells which damage the epithelial cells.
- T helper cells are recruited via IL15 and these activate B cells to produce anti-tTG and EMA antibodies.
What are features of intestinal lymphangiectasia?
- Protein losing enteropathy and steatorrhoea.
- Primary or secondary to disease causing obstruction to intestinal lymphatic drainage.
- Associated with Noonans and Turners.
- Loss of protein-rich lymph containing albumin, globulins and lymphocytes.
- Leads to faecal fat loss and hypoproteinaemia (without proteinuria or hepatic dysfunction), hypoalbuminaemia and lymphopenia.
What are the most common causes of acute pancreatitis in childhood?
- Blunt abdominal trauma.
- Multisystem disease.
- Biliary stones.
- Drug toxicity.
What are features of Meckel divericulum?
- Remnant of embryonic yolk sac or vitelline duct.
- Seperates from the intestine at 6w gestation.
- If this fails a 3-6cm outpouching of the ileum forms - this is lined with stomach epithelium.
- First decade but usually first 2y, painless rectal bleeding (red current jelly or brick coloured).
- Associated with anaemia.
- Can be a lead point for an intussusception.
- Diagnosis with 99m Technetium pertechnetate scan.
What are symptoms of hepatic veno-occlusive disease?
- Jaundice, weight gain, painful hepatomegaly, ascites.
- Acute GVHD typically occurs later (14-21 days post SCT).
- In acute GVHD, ALT rises in absence of elevated bilirubin, ALP and GGT (mimicking hepatitis).
What are the Seattle Diagnostic criteria of hepatic veno-occlusive disease?
- Timing post SCT.
- High bilirubin.
- Hepatomegaly.
- RUQ pain.
- Ascites/weight gain.
- Diagnosis rests on exclusion of GVHD, congestive cardiomyopathy, constrictive cardiomyopathy and Budd Chiari syndrome.
What causes superior mesenteric artery syndrome?
- Compression of the 3rd duodenal segment by the SMA against the aorta.
- Weight loss and malnutrition can cause mesenteric fat depletion which collapses the duodenum within a narrowed aortomesenteric angle.
Which gastointestinal organism is most efficient at breaking down urea?
- PUNCH
- Proteus, Klebsiella, Ureaplasmin, Nocardia, Cryptococcus, Helicobacter pylori.
- H. pylori depends upon urease to adhere to allow it to survive and proliferate in the gastric milieu.
- Hydrolyses gastric luminal urea to form ammonia that helps neutralise gastric acid and form a protective cloud.
- Urease makes up >5% of the organisms total protein weight.
- Diagnostic tests for H. pylori include biopsy urease testing and urea breath testing.
What are laboratory findings in refeeding syndrome?
- Hypophosphataemia.
- Abnormal sodium and fluid balance.
- Thiamine deficiency.
- Hypokalaemia and hypomagnesaemia.
What are the 3 most important disaccharides?
- Sucrose.
- Maltose.
- Lactose.
How is sucrose produced?
- Fructose and glucose held together by an a bond.
- Found in table sugar.
How is maltose produced?
- Breakdown of starch by salivary and pancreatic amylase.
- Composed of 2x glucose with an a bond.
What makes up lactose?
- Glucose and galactose.
Why is there absence of neural innervation in Hirschsprungs?
- Arrest of neuroblast migration from proximal to distal bowel.
What percentage of children with Hirschsprungs have total bowel agangliosis?
- 5%.
- 10-15% have long segement involvement.
- Limited to rectosigmoid in 80%.
What is found histologically in Hirshsprungs?
- Absence of Meissner and Auerbach plexus.
- High concentrations of ACh between muscular layers and submucosa.
