GI 2 Flashcards
what is the oesophageal clinical presentation of GORD?
- heartburn
- belching
- food/acid brash (food, acid or bile regurgitation)
- water brash (increased salivation)
- odynophagia (painful swallowing)
what is heartburn? what are some features of it?
- burning chest pain that is aggravated by bending, stooping and lying down which promotes acid exposure and may be relieved by antacids
- worse with hot drinks or alcohol
- seldom radiates to the arms
what is odynophagia?
painful swallowing
what are extra-oesophageal clinical presentations of GORD?
- nocturnal asthma
- chronic cough
- laryngitis (hoarseness and throat clearing)
- sinusitis
what are differential diagnoses of GORD?
- coronary artery disease
- biliary colic
- peptic ulcer disease
- malignancy
when can GORD be diagnosed without investigation?
- when there are no alarm bell signs, e.g. weight loss, haematemesis, dysphagia
- patients under 45 can safely be treated initially without investigation
what is used to investigate and diagnose GORD?
- endoscopy
- barium swallow may show hiatus hernia
what are the aims of investigations of GORD?
assess oesophagitis (inflammation of oesophagus) and hiatal hernia by endoscopy: - if there is oesophagitis or Barrett’s oesophagus then reflux is confirmed
document reflux by intraluminal monitoring:
- 24hr oesophageal pH monitoring is helpful in diagnosing GORD when endoscopy is normal or just prior to surgery to confirm reflux
- also helpful if there is no response to proton-pump inhibitors
what classification is used to assess GORD?
use Los Angeles classification of GORD/Oesophagitis when doing endoscopy to gauge extent of damage
what lifestyle changes can be used to treat GORD?
- encourage weight loss
- smoking cessation
- small, regular meals
- avoid; hot drinks, alcohol, citrus fruits and eating less than 3 hours before bed
what drugs are used to treat GORD? how do they work?
- antacids e.g. magnesium triscilicate mixture: relieves symptoms by forming a gel or ‘foam raft’ with gastric contents to reduce reflux, note: side effect of magnesium containing antacids is diarrhoea
- alginates e.g. gaviscon; relieves symptoms
- proton pump inhibitor (PPI) e.g. lanzoprazole to reduce gastric acid production
- H2 receptor antagonists e.g. cimetidine
what surgery can be used to treat GORD? when is it used?
nissen fundoplication; aims to laparoscopically increase the resting LOS pressure
- only in severe GORD
- use when not responding to therapy
- complications include dysphagia and bloating
what are complications of GORD?
peptic stricture and Barrett’s oesophagus
what is peptic stricture? what is its clinical presentation and treatment?
- oesophagitis resulting from gastric (peptic) acid exposure resulting in the narrowing and stricture of the oesophagus
- usually occurs in patients over 60
- presents as gradually worsening dysphagia
- treat with endoscopic dilatation and long term PPI therapy
what is barrett’s oesophagus? what is its clinical presentation?
- GORD may induce barrett’s oesophagus
- distal oesophageal epithelium undergoes metaplasia from squamous to columnar epithelium
- always a hiatus hernia present
- risk of progressing to oesophageal cancer; is premalignant for adenocarcinoma of the oesophagus
what is a Mallory-Weiss tear? what is its epidemiology?
- this is a linear mucosal tear occurring at the oesophagogastric junction and is produced by a sudden increase in intra-abdominal pressure
- often follows a bout of coughing or retching and is classically seen after alcoholic ‘dry heaves’
- most common in males
- seen mainly in age 20-50
what are risk factors for Mallory-Weiss tears?
- alcoholism
- forceful vomiting
- eating disorders
- male
- NSAID abuse
what are clinical features of Mallory-Weiss tears?
- vomiting
- haematemesis after vomiting
- retching
- postural hypotension
- dizziness
what are differential diagnoses of Mallory-Weiss tears?
- gastroenteritis
- peptic ulcer
- cancer
- oesophageal varices
what is used to diagnose Mallory-Weiss tears?
endoscopy to confirm
what is the treatment of Mallory-Weiss tears?
- most bleeds are minor and heal in 24 hours
- haemorrhage may be large but tends to stop spontaneously
- if surgery is required then it involves the oversewing of the tear but this is rarely needed
what is dyspepsia?
one or more of the following:
- postprandial fullness
- early satiation
- epigastric pain or burning for more than 4 weeks
an inexact term used to describe a number of upper abdominal symptoms such as heartburn, acidity, epigastric pain or discomfort, fullness or belching
what is the epidemiology of dyspepsia?
- dyspepsia is a common complaint affecting up to 25% of the population each year
- patients may say it’s indigestion
what are causes of dyspepsia?
- disorders of the GI tract - the most common is functional dyspepsia that affects around 75% with no known cause
- other causes are peptic ulcers
what is the clinical presentation of dyspepsia?
- reflux when lying flat
- heartburn
- acid taste due to reflux
- bloating
- indigestion
what are red flag alarm symptoms in dyspepsia for cancer?
- unexplained weight loss
- anaemia
- evidence of GI bleeding e.g. melaena (dark tar like black stools) or haematemesis
- dysphagia
- upper abdominal mass
- persistent vomiting
what is the history/differentials of dyspepsia?
- heartburn/regurgitation/cough: possibly GORD
- alarm symptoms or family history can be an indicator of possible malignancy
- onset; acute vs. chronic
- age; over 55 is a red flag and thus means increased risk of cancer
- relationship to food
what is the relationship to food of dyspepsia?
- early postprandial pain - could be due to gastritis, GORD or gastric carcinoma
- postprandial pain could be due to a gastric ulcer
- pain that is relieved by milk could also be a sign of gastric ulcer
what is the management of dyspepsia?
- reassurance
- dietary review
- antidepressants e.g. SSRIs
- look for Helicobacter pylori using faecal antigen testing or breath test
- endoscopy
what is the structure of the mucosal lining of the stomach?
- can stretch in size with feeding
- the greater curvature of the undistended stomach has thick folds called rugae
- the mucosa of the upper two thirds of the stomach contain:
• parietal cells - secrete HCl
• chief cells - produce pepsinogen and thus initiate proteolysis - the digestion of proteins
• enterochromaffin-like (ECL) cells - releases histamine (stimulates acid release)
what cells does the antral mucosa of the stomach contain?
- mucus secreting cells - secrete mucin (protects gastric mucosa) and bicarbonate
- G cells - secrete gastrin which stimulates acid release
- D cells - secrete somatostatin which suppresses acid secretion
what is the mucosal barrier of the stomach? what is its structure and function?
- is made up of the plasma membranes of the mucosal cells and the mucus layer (made up of mucin), protects the gastric epithelium from damage by acid and, for example, alcohol, aspirin, NSAIDs and bile salts
- prostaglandins stimulate the secretion of mucus and their synthesis is inhhibited by aspirin and NSAIDs, which inhibit cyclo-oxygenase
what is the structure/function of the duodenal mucosa?
- has villi like the rest of the small bowel and also contains Brunner’s glands which secrete alkaline mucus
- this, along with the pancreatic and biliary secretions, helps to neutralise the acid secretion from the stomach when it reaches the duodenum
what is a peptic ulcer?
consists of a break in the superficial epithelial cells which penetrates down to the muscularis mucosa of either the stomach or the duodenum; there is a
fibrous base and an increase in inflammatory cells
where are duodenal and gastric peptic ulcers often seen?
- duodenal ulcers most commonly seen in duodenal cap
- gastric ulcers most commonly found on the lesser curve of the stomach but can be found anywhere in the stomach
what is the epidemiology of peptic ulcer disease?
- duodenal ulcers affect around 10% of the adult population and are 2-3 times more common than gastric ulcers
- more common in the elderly
- more common in developing countries due to Helicobacter pylori
- ulcers due to NSAID use is increasing
- decline in incidence in men and increasing in women
what are the main causes of peptic ulcer disease?
- Helicobacter pylori infection
- drugs e.g. NSAIDs (including aspirin), steroids and SSRIs
- increased gastric acid secretion (minor)
- smoking (minor)
- delayed gastric emptying
- blood group O
what is the pathophysiology of peptic ulcer disease?
- ulcers result in gastritis
- usually the gastric mucosa is protected by a layer of mucin that is produced by gastric cells
- NSAIDs e.g. naproxen and aspirin
- Helicobacter pylori
- ischaemia of the gastric cells
- too much acid production
- alcohol has a direct toxic effect on gastric cells in high concentrations
how can NSAIDs lead to peptic ulcer disease?
e.g. naproxen and aspirin
• mucous secretion is stimulated by prostaglandins (in inflamed tissue, prostaglandin triggers inflammatory response thus inhibition = less inflammation)
• cyclo-oxygenase 1 is needed for prostaglandin synthesis
• NSAIDs inhibit cylclo-oxygenase 1
• thus reduced mucosal defence
how can Helicobacter pylori lead to peptic ulcer disease?
- highly adapted to the stomach environment and exclusively colonises gastric epithelium and inhabits the mucous layer/just beneath it
- causes major destruction to the protective mucin layer
- causes decrease in duodenal HCO3- thereby increasing the acidity of the stomach as there will be less alkali to buffer the acid
- secretes urease, splitting urea into CO2 and ammonia
- ammonia + H+ = ammonium
- ammonium is toxic to gastric mucosa resulting in less mucous produced
- secreted proteases, phospholipase and vacuolating cytotoxin A can then begin attacking the gastric epithelium further reducing mucous production
- results in an inflammatory response and less mucosal defence
- also increases gastrin release, causing more acid secretion from parietal cells and also triggering the release of histamine which further increases acid secretion
- also increases parietal cell mass meaning more acid production
- also decreases somatostatin release (which reduces acid secretion) resulting in increased acid release
- increased acidity overwhelms the protective mucin layer resulting in mucosal damage and ulceration
what are the overall effects of H. pylori?
- inflammation e.g. antral gastritis
- gastric cancer
- peptic ulcers
how can ischaemia of the gastric cells lead to peptic ulcer disease?
- causes gastric cells to produce less mucin resulting in less protection from acid, meaning acid is able to damage mucosa and cause an ulcer
- caused by low blood pressure or atherosclerosis
how can too much acid production lead to peptic ulcer disease?
- too much acid overwhelms mucin and results in ulceration
- stress can result in increased acid production
- PPIs and H2 blockers used to treat this
what is the clinical presentation of peptic ulcer disease?
- recurrent burning epigastric pain
- nausea may accompany the pain
- anorexia and weight loss, particularly with gastric ulcers
what are features of recurrent burning epigastric pain in peptic ulcer pain?
- if patient points with a single finger to the epigastrium as the site of pain, then this is strongly suggestive of peptic ulcer disease
- pain of duodenal ulcers classically occurs at night (as well as during the day) and is worse when the patient is hungry
- pain in both gastric and duodenal ulcers can be relieved by antacids
what are complications of peptic ulcers?
- in duodenal ulcers, the ulcer can get deeper and deeper until it hits an artery, most commonly the gastroduodenal artery, which can result in massive haemorrhage, presents as an emergency
- can result in peritonitis as acid enters peritoneum; will see air under diaphragm on erect X-ray
- can result in acute pancreatitis if the ulcer hits the pancreas
what is the diagnosis of peptic ulcer disease?
- if patients is under 55 then carry out non-invasive testing e.g. serological test, breath test or stool antigen testing, if test is positive then start eradication immediately
- usually an endoscopy is not necessary, but if found to have a gastric ulcer then re-scope 6-8 weeks later to ensure there is no malignancy
- endoscopy is essential is all red flag patients and those who are over 55
- non-invasive H. pylori testing (serology, C-urea breath test, stool antigen test)
how is serology used as a non-invasive H. pylori test for peptic ulcer disease?
detects IgG antibodies - not useful for confirming eradication or presence of current infection since IgG takes 1 year to fall by 50%
how is a C-urea breath test used as a non-invasive H. pylori test for peptic ulcer disease?
- quick and reliable test for H.pylori
- measures CO2 in breath after the ingestion of C-Urea
- used to monitor infection after eradication
- highly sensitive and specific
- no antibiotics or proton-pump inhibitors (PPIs) before test
how is a stool antigen used as a non-invasive H. pylori test for peptic ulcer disease?
- immunoassay using monoclonal antibodies for detection of H. pylori
- monitors the efficacy of eradication therapy
- patients should be off PPIs for 2 weeks before
how is biopsy used as an invasive H. pylori test for peptic ulcer disease?
• histology - direct visualisation of H.pylori, reduced if on PPIs
• biopsy urease test:
- H. pylori produces urease
- splits urea to release ammonia which will raise pH of the solution and causes a rapid colour change of yellow to red
- no PPIs or antibiotics should be used before since this will give false negatives
what is the treatment of peptic ulcer disease?
- lifestyle adjustments (reduce stress, avoid irritating foods, reduce smoking)
- stop NSAIDs
- H.pylori eradication (7-14 days)
- H2 antagonists to reduce acid release
- surgery if complications arise such as haemorrhage
how is H. pylori eradication confirmed? how long does it take?
- 7-14 days
- confirmed by urea breath or faecal antigen test
what is used for H. pylori eradication?
triple therapy
- PPI for acid suppression e.g. lansoprazole or omeprazoel
- plus 2 of: metronidazole, clarithromycin, amoxicillin, tetracycline, bismuth
- note: amoxicillin and tetracycline have low resistance, and clarithromycin has high resistance
- quinolones e.g. ciprofloxacin, furozolidone and rifabutin are used when standard regimens have failed as rescue therapy
what is a varice?
dilated vein which is at risk of rupture resulting in haemorrhage and can result in GI bleeding
what is the function of the hepatic portal vein?
- carries nutrient rich blood from the GI tract, gallbladder, pancreas and spleen to the liver
- rich in nutrients that have been extracted from food and the liver processes these nutrients; it also filters toxins that may have been ingested alongside the food
- the blood leaves the liver to the heart in the hepatic veins via the IVC
what is the normal pressure of the hepatic portal vein?
5-8mmHg
how is portal hypertension classified? what are the classifications?
according to the site of obstruction
- pre-hepatic; blockage of the hepatic portal vein before the liver
- intra-hepatic; distortion of the liver architecture, either pre-sinusoidal (e.g. schistosomiasis) or post-sinusoidal (e.g. cirrhosis)
- post-hepatic; venous blockage outside the liver (rare)
how are varices formed within the systemic venous system?
- as portal pressure rises above 10-12mmHg, the compliant venous system dilates and varices form within the systemic venous system
- these can form at the gastro-oesophageal junction, rectum, left renal vein, diaphragm and the anterior abdominal wall via the umbilical vein
- gastro-oesophageal varices are superficial and tend to rupture, resulting in GI bleeding, usually when pressure exceeds 12mmHg
what is the epidemiology of gastro-oesophageal varices? where do they tend to develop?
- around 90% of patients with cirrhosis will develop gastro-oesophageal varices over 10 years, but only a third of these will bleed
- bleeding is likely to occur with large varices, or those with red flag signs at endoscopy and in severe liver disease
- varices tend to develop in the lower oesophagus and gastric cardia
what are the main causes of gastro-oesophageal varices?
- alcohol and viral cirrhosis
- portal hypertension
what are causes of pre-hepatic portal hypertension?
thrombosis in portal or splenic vein
what are causes of intra-hepatic portal hypertension?
- cirrhosis (commonest cause in UK)
- schistosomiasis (commonest cause worldwide)
- sarcoid
- congenital hepatic fibrosis
what are causes of post-hepatic portal hypertension?
- Budd-Chiari syndrome (hepatic vein obstruction by tumour or thrombosis)
- right heart failure
- constrictive pericarditis
what is Budd-Chiari syndrome?
hepatic vein obstruction by tumour or thrombosis
- causes post-hepatic portal hypertension
what are risk factors for gastro-oesophageal varices?
- cirrhosis
- portal hypertension
- schistosomiasis infection
- alcoholism
what is the pathophysiology of gastro-oesophageal varices?
- following liver injury and fibrogenesis, the contraction of activated myofibroblasts (mediated by endothelin, nitric oxide and prostaglandins) contributes to increased resistance to blood flow
- this leads to portal hypertension → splanchnic vasodilation → drop in BP → increased cardiac output to compensate for BP drop → salt and water retention to increase blood volume and compensation → hyperdynamic circulation → formation of collaterals between the portal and systemic systems → gastro-oesophageal varices develop once portal pressure is above 10mmHg - can occur rapidly and result in major haemorrhage
what is the clinical presentation of a ruptured gastro-oesophageal varices?
- haematemesis
- abdominal pain
- shock - if major blood loss
- fresh rectal bleeding - associated with shock in acute massive GI bleed
- hypotension and tachycardia
- pallor
- suspect varices as the cause of GI bleeding if there is alcohol abuse or cirrhosis
what is the clinical presentation of gastro-oesophageal varices?
- signs of rupture
- signs of chronic liver damage e.g. jaundice, increased bruising and ascites
- splenomegaly
- ascites
- hyponatraemia
what is used to diagnose gastro-oesophageal varices?
endoscopy to find bleeding source
what is the treatment of gastro-oesophageal varices?
- resuscitate until haemodynamically stable
- if anaemic then do blood transfusion aiming to get Hb to 80g/L
- correct clotting abnormalities with vitamin K and platelet transfusion
- vasopressin e.g. IV terlipressin or somatostatin
- prophylactic antibiotics
- variceal banding
- balloon tamponade to reduce bleeding
- transjugular intrahepatic portoclaval shunt (TIPS); a shunt between the systemic and portal systems which reduces sinusoidal and portal vein pressure
what is TIPS?
transjugular intrahepatic portoclaval shunt
- artificial channel within the liver that establishes communication between the inflow portal vein and the outflow hepatic vein
- uses endoscope
- jugular vein is usual entry site
- used to treat varices
how can gastro-oesophageal varices be prevented?
- non-selective beta-blockade to reduce resting pulse rate to decrease portal pressure
- variceal banding repeatedly
- liver transplant
what is the epidemiology of achalasia?
- characterised by oesophageal aperistalsis and impaired relaxation of the lower oesophageal sphincter
- the lower oesophageal pressure is elevated in more than half of patients
- incidence is 1 in 100,000 and is equal in both males and females
- occurs at all ages but rare in childhood
- patients usually have a long history of intermittent dysphagia characteristically for both liquids and solids from the onset
- cause is unknown
what is achalasia?
failure of smooth muscle fibres in the oesophagus to relax, which can cause the LOS to remain closed
what is the pathophysiology of achalasia?
the LOS fails to relax due to degeneration of the
mesenteric plexus of the oesophagus, with reduction of ganglion cell numbers
what is the clinical presentation of achalasia?
- dysphagia for fluids and solids
- regurgitation of food particularly at night and aspiration pneumonia is a complication
- substernal cramps
- weight loss (usually minimal)
- spontaneous chest pain occurs due to oesophageal ‘spasm’; may be misdiagnosed as cardiac pain
how is achalasia diagnosed?
CXR
• dilated oesophagus
• may be fluid level behind/above the heart
barium swallow
• shows lack of peristalsis
• lower end shows a ‘birds beak’ due to failure of sphincter to relax
manometry
• confirms diagnosis
• shows aperistalsis of the oesophagus and failure of relaxation of the LOS
CT and oesophagoscopy used to rule out carcinoma at the lower end of the oesophagus which can produce a similar x-ray appearance
what is treatment of achalasia?
- relief of symptoms
- medical treatment to relax the LOS e.g. nifepidine,
nitrates or sildenafil - surgery
what is the surgical treatment of achalasia?
- endoscopic balloon dilation to open sphincter
- Heller’s cardiomyotomy - the surgical division of the lower oesophageal sphincter and then PPIs
- botox injection into sphincter to relax it (effects wear off)
what are complications of treatment of achalasia?
there is a slight increase in the incidence of squamous carcinoma of the oesophagus in both treated and untreated cases
what is scleroderma?
- group of autoimmune disease that may result in changes to skin, blood vessels, muscles, and internal organs
- increased synthesis of collagen, damage to small blood vessels, activation of T lymphocytes and production of altered connective tissues
- multi-system disease
what is the epidemiology of scleroderma/systemic sclerosis?
- more common in females than males
- peak incidence is between 30 and 50
- rare in children
- there is oesophageal involvement in almost all patients with this disease
what are risk factors for scleroderma/systemic sclerosis?
- vinyl chloride
- silica dust
what is the pathophysiology of scleroderma/systemic sclerosis?
- diminished peristalsis and oesophageal clearance due to the replacement of the smooth muscle by fibrous tissue
- LOS pressure is decreased thereby allowing GORD with consequent mucosal damage
- strictures may develop
what is the clinical presentation of scleroderma/systemic sclerosis?
- initially there are no symptoms
- dysphagia and heartburn occur as the oesophagus becomes more severely
involved
how is scleroderma/systemic sclerosis diagnosed?
- barium swallow
- CXR
- manometry
what is the treatment of scleroderma/systemic sclerosis?
same as for GORD. e.g. PPIs
what is gastritis? what does gastropathy indicate?
- inflammation of the lining of the stomach
- may occur as a short episode or have long duration
- inflammation that is associated with mucosal injury
- gastropathy indicates epithelial cell damage and regeneration without inflammation; commonest cause is mucosal damage associated with aspirin/NSAIDs
what are causes of gastritis?
- Helicobacter pylori infection
- autoimmune gastritis
- viruses e.g. cytomegalovirus and herpes simplex
- duodenogastric reflux, where bile salts enter stomach and damage mucin protection, resulting in gastritis
- specific causes e.g. Crohn’s (more common in children than adults)
- mucosal ischaemia; reduced blood supply to mucosal cells can mean less mucin produced so acid can induce gastritis
- increased acid; can overwhelm mucin resulting in gastritis, stress can increase acid production
- aspirin and NSAIDs
- alcohol
what is the pathophysiology of gastritis caused by H. pylori?
- most common cause
- causes severe inflammatory response
- gastric mucus degradation and increased mucosal permeability, which is directly cytotoxic to the gastric epithelium
what is the pathophysiology of autoimmune gastritis?
affects the fundus and body of the stomach leading to
atrophic gastritis and loss of parietal cells with intrinsic factor deficiency resulting in pernicious anaemia
what is the pathophysiology of gastritis caused by aspirin and NSAIDs?
NSAIDs will inhibit prostaglandins (which stimulate mucus production) via the inhibition of cyclo-oxygenase resulting in less mucus production and thus gastritis
what is the clinical presentation of gastritis?
- nausea or recurrent upset stomach
- abdominal bloating
- epigastric pain
- vomiting
- indigestion
- haematemesis
what are differential diagnoses of gastritis?
- peptic ulcer disease (PUD)
- GORD
- non-ulcer dyspepsia
- gastric lymphoma
- gastric carcinoma
how is gastritis diagnosed?
- endoscopy
- biopsy
- H.pylori urea breath test
- H.pylori stool antigen test
what is the treatment of gastritis?
- remove causative agents
- reduce stress
- H. pylori eradication (7-14 days)
- H2 antagonists and PPIs to reduce acid release
- antacids
what is malabsorption?
the failure to fully absorb nutrients due to the destruction of epithelium or due to a problem in the lumen meaning food cannot be digested
what are disorders of the small intestine that result in malabsorption?
- coeliac disease
- tropical sprue
- Crohn’s
- parasite infection
what are causes of malabsorption?
- defective intraluminal digestion
- insufficient absorptive area
- lack of digestive enzymes
- defective epithelial transport
- lymphatic obstruction
how can defective intraluminal digestion cause malabsorption?
- pancreatic insufficiency
- defective bile secretion
- bacterial overgrowth
how can pancreatic insufficiency cause defective intraluminal digestion causing malabsorption?
- pancreas produce majority of digestive enzymes such as amylase
- pancreatitis causes damage to most of the glandular pancreas meaning less or no enzymes are released
- cystic fibrosis results in the blockage of the pancreatic duct due to excess mucus, meaning enzymes are not released
how can defective bile secretion cause defective intraluminal digestion which causes malabsorption?
- lack of fat solubilisation
- biliary obstruction
- ileal resection (bile salts are reabsorbed in the terminal ileum so if removed then bile salt reuptake will be decreased)
how can insufficient absorptive area cause malabsorption?
- essentially anything that damages microvilli and villi thereby reducing absorptive surface area and thus absorption potential
- Coeliac disease
- Crohn’s
- giardia lamblia
- surgery for small bowel infarction
how can giardia lamblia cause insufficient absorptive area which causes malabsorption?
- extensive surface parasitisation of the villi and microvilli
- parasites coat the surface of the villi thus food cannot be absorbed
how can lack of digestive enzymes cause malabsorption?
- disaccharidase deficiency (lactose intolerance) - cannot break down the lactose in milk into glucose which can then be absorbed. the undigested lactose passes into the colon where it is then eaten up by bacteria and CO2 is released leading to wind and diarrhoea
- bacterial overgrowth resulting in brush border damage
how can defective epithelial transport cause malabsorption?
- abetalipoproteinaemia - lack of transporter protein to transport lipoprotein across cell
- primary bile acid malabsorption - mutations in bile acid transporter protein
how can lymphatic obstruction cause malabsorption?
- lymphoma
- TB
what is Coeliac disease?
• condition in where there is inflammation of the mucosa of the upper small bowel that improves when gluten is withdrawn from the diet and relapses when gluten is reintroduced
• T-cell mediated autoimmune disease of the small bowel in which prolamin (alcohol-soluble proteins in wheat, barley, rye and oats) intolerance causes villous
atrophy and malabsorption
what are types of prolamins?
gliadin in wheat, hordeins in barley and secalins in rye
what is the epidemiology of Coeliac disease?
- around 1% of population affected
- occurs at any age but peaks in infancy and 50-60yrs
- affects males and females equally
- 10% risk in 1st degree relatives and 30% risk in siblings
what are risk factors for Coeliac disease?
- other autoimmune diseases: type 1 diabetes, thyroid disease, Sjorgrens
- IgA deficiency
- breast feeding
- age of introduction to gluten into diet
- rotavirus infection in infancy increases risk
what is the pathophysiology of Coeliac disease?
- in wheat and in gluten the prolamin a-gliadin is toxic and resistant to digestion by pepsin and chymotrypsin because of their high glutamine and proline content, and it remains in the intestinal lumen thereby triggering
immune responses - the gliadin peptides pass through the epithelium and are deaminated by tissue transglutaminase, which increases their immunogenicity
- the gliadin peptides bind to antigen-presenting cells which interact with CD4+ T cells in the lamina propria via HLA class II DQ2 or DQ8
- these two HLA class II molecules DQ2 (95%) or DQ8 (5%) activate the gluten-sensitive T cells
- these T cells produce pro-inflammatory cytokines and initiate an inflammatory cascade
- the cascade releases metalloproteinkinases and other mediators, which contribute to the villous atrophy, crypt hyperplasia and intraepithelial lymphocytes that are typical of the disease and result in malabsorption
- proximal small bowel mucosa is predominantly affected
- this mucosal damage means that B12, folate and iron cannot be absorbed resulting in anaemia
- mucosal damage decreases in severity towards the ileum as gluten is digested into small ‘non-toxic’ fragments
what HLA molecules contribute to Coeliac disease?
- HLA class II molecules DQ2 or DQ8
- these two HLA class II molecules DQ2 (95%) or DQ8 (5%) activate the gluten-sensitive T cells
- these T cells produce pro-inflammatory cytokines and initiate an inflammatory cascade
what is the clinical presentation of Coeliac disease?
- 1/3 are asymptomatic and only detected on routine blood tests (raised MCV)
- stinking stools/fatty stools (steatorrhoea)
- diarrhoea
- abdominal pain
- bloating
- nausea and vomiting
- angular stomatitis
- weight loss
- fatigue
- anaemia
- osteomalacia; softening of bones due to impaired bone metabolism due to lack of phosphate, calcium and vitamin D leading to osteoporosis (40-60% risk
in untreated patients leading to fracture risk) - dermatitis hepetiformis; red raised patches, often with blisters that burst on scratching, commonly seen on elbows, knees and buttocks
what is dermatitis hepetiformis?
- chronic autoimmune blistering skin condition
- characterised by blisters filled with watery fluid
- itchy
- cutaneous manifestation of Coeliac disease
- red raised patches
- commonly seen on elbows, knees and buttocks
how can Coeliac be diagnosed?
- should maintain gluten for at least 6 weeks before testing to get true results
- duodenal biopsy is gold standard for diagnosis
- serum antibody testing
what is seen on an FBC in Coeliac disease?
- low Hb
- low B12
- low ferritin
what is seen on a duodenal biopsy in Coeliac disease?
- see villous atrophy, crypt hyperplasia and increased intraepithelial WCC
- all reverse on gluten free diet
what are indications for serum antibody testing to detect Coeliac disease?
- persistent diarrhoea
- folate or iron deficiency
- family history of Coeliac disease or associated autoimmune disease
what is serum antibody testing for Coeliac disease?
- 95% sensitive unless patient is IgA deficient
- endomysial antibody (EMA)
- tissue transglutaminase antibody (tTG)
- both are IgA antibodies
- these correlate with the severity of mucosal damage and can thus be used for dietary monitoring
what is the treatment of Coeliac disease?
- lifelong gluten free diet; use serum antibody testing for monitoring
- correction of vitamin and mineral deficiencies e.g. B12, folate, iron, calcium and vitamin D
- DEXA scan to monitor osteoporotic risk
what are features of lifelong gluten free diets used to treat Coeliac disease?
- eliminate wheat, barley and rye; see results in days/weeks
- poor compliance is main reason for recurrent issues
- oats usually tolerated unless contaminated with flour during production
- meat, dairy product, fruits and vegetables are all gluten-free
what are complications of treatment of Coeliac disease?
- a few patients do not improve on a strict diet and are said to have non-responsive coeliac disease
- anaemia
- secondary lactose intolerance
- T-cell lymphoma
- increased risk of malignancy (gastric, oesophageal, bladder, breast and brain) due to increased cell turnover
- osteoporosis
what is tropical sprue?
- malabsorption disease commonly found in tropical regions, marked with abnormal flattening of the villi and inflammation of the lining of the small intestine
- severe malabsorption of two or more substances accompanied by diarrhoea and malnutrition
what is the epidemiology of tropical sprue?
- the term tropical sprue is reserved for severe malabsorption (of two or more substances) accompanied by diarrhoea and malnutrition
- occurs in residents or visitors to tropical areas where the disease is endemic; most of Asia, some Caribbean islands, Puerto Rico and parts of South America
- cause is unknown but is likely to be infective because the disease occurs in epidemics and patients improve on antibiotics
what is the pathophysiology of tropical sprue?
- villous atrophy with malabsorption
- onset is acute and occurs either a few days or many years after being in the tropics
- epidemics can break out in villages, affecting thousands of people at the same time
what is the clinical presentation of tropical sprue?
- diarrhoea
- anorexia
- severe malabsorption
- weight loss
- abdominal distension
- the onset can also be insidious with chronic diarrhoea and evidence of nutritional deficiency
how is tropical sprue diagnosed? how is it different from Coeliac disease?
- exclude acute infective causes of diarrhoea e.g. Giardia intestinalis, which can produce similar symptoms
- bloods: anaemia due to malabsorption of B12, folate and iron
- jejunal biopsy: jejunal mucosa is abnormal showing partial villous atrophy
what is the treatment/prognosis of tropical sprue?
- leave area
- folic acid daily and antibiotics for up to 6 months
- severe cases require resuscitation with fluids and electrolytes for dehydration and nutritional deficiencies should be corrected and B12 given
- excellent prognosis
- mortality is only associated with water and electrolyte depletion particularly in epidemics
what are the two forms of inflammatory bowel disease?
both autoimmune conditions:
- ulcerative colitis (UC), which affects only the colon
- crohn’s disease (CD), can affect any part of the GI tract (mouth to anus)
what is the epidemiology of inflammatory bowel disease?
jewish people are more prone to IBD than any other ethnic group
when does IBD occur?
IBD occurs when the mucosal immune system exerts an inappropriate response to luminal antigens, such as bacteria, which may enter the mucosa via a leaky epithelium
what is ulcerative colitis? what areas can it affect?
• relapsing and remitting inflammatory disorder of the colonic mucosa
• it may affect just the rectum; proctitis (50%)
• it may affect the rectum and left colon; left-sided colitis (30%)
• it may affect the entire colon (entire large bowel) up to
the ileocaecal valve; pancolitis/extensive colitis
• it never affects proximal to the ileocaecal valve
what is the epidemiology of ulcerative colitis?
- highest incidence and prevalence in Northern Europe, UK and North America
- higher incidence than Crohn’s per year
- affects males and females equally
- presentation mostly at 15-30 years
- is 3 times more common in non/ex-smokers; symptoms may relapse on cessation
- cause is unknown
- 1 in 6 will have a first degree relative with UC
- an appendicectomy appears to be protective against the development of UC, especially if performed for appendicitis before 20yrs. It also leads to a lower incidence of colectomy and reduced need for immunosuppressive therapy
what are risk factors for UC?
- family history
- NSAIDs
- chronic stress and depression triggers flares
what is the macroscopic pathophysiology of UC?
- affects only the colon up to the ileocaecal valve
- begins in the rectum and extends
- circumferential and continuous inflammation - no skip lesions
- mucosa looks reddened and inflamed and bleeds easily (friability)
- ulcers and pseudo-polyps (regenerating mucosa) in severe disease
what is the microscopic pathophysiology of UC?
- mucosal inflammation; inflammation does not go deeper e.g. transmural
- no granulomata (rare)
- depleted goblet cells
- increased crypt abscesses
what is the clinical presentation of UC?
- remissions and exacerbations
- restricted pain usually in lower left quadrant
- episodic or chronic diarrhoea with blood and mucus
- cramps
- bowel frequency linked to severity
- in acute UC there may be fever, tachycardia and tender distended abdomen
- in acute attack patients have bloody diarrhoea (passing 10-20 liquid stools per day), diarrhoea also occurs at night, with urgency and incontinence that is
severely disabling - extraintestinal signs; clubbing, aphthous oral ulcers, erythema nodusum and amyloidosis
what are extraintestinal signs of UC?
- clubbing
- aphthous oral ulcers
- erythema nododum
- amyloidosis
what are complications of UC in the liver?
- fatty change
- chronic pericholangitis
- sclerosing cholangitis
what are complications of UC in the colon?
- blood loss
- perforation
- toxic dilatation
- colorectal cancer
what are complications of UC in the skin?
- erythema nodosum
- pyoderma gangrenosum
what are complications of UC in the joints?
- ankylosing spondylitis
- arthritis
what are complications of UC in the eyes?
- iritis
- uveitis
- episcleritis
how can UC be diagnosed?
- blood tests
- stool samples to exclude C. diff and Campylobacter etc
- faecal calprotectin; indicates IBD but not specific
- colonoscopy with mucosal biopsy
- abdominal X-ray
what is seen on blood tests in UC?
- WCC and platelets raised in moderate/severe attacks
- iron deficiency anaemia
- ESR and CRP raised
- liver biochemistry may be abnormal
- hypoalbuminaemia is severe disease
- pANCA may be positive (in Crohn’s it’s negative)
how can colonscopy be used to diagnose UC?
- gold standard for diagnosis
- allows for assessment of disease activity and extent
- can see inflammatory infiltrate, goblet cell depletion, crypt abscesses and mucosal ulcers
what is seen on an abdominal X-ray in UC?
- done in all patients suffering acute severe attacks to exclude colonic dilatation
- useful when UC too severe for colonoscopy
what is the treatment of UC?
- aim is to induce remission
- aminosalicylate which acts topically in the colonic lumen
- the active component of these drugs is 5-aminosalicylic acid (5-ASA) which is absorbed in the small intestine
- the aminosalicylate preparations are designed to deliver the active 5-ASA to the colon by binding to something else
- commonly prescribed 5-ASA aminosalicylates are sulfalazine, mesalazine or olsalazine
what are the commonly prescribed 5-ASAs in UC?
- sulfalazine
- mesalazine
- olsalazine
what is treatment of mild/moderate UC?
- oral 5-ASA; first line for left sided/extensive
- rectal 5-ASA for proctitis
- glucocorticoid if no response to 5-ASA
what is treatment of severe UC?
glucocorticoids
what is treatment of severe UC with systemic features e.g. liver, skin, eye involvement?
- hydrocortisone
- ciclosporin
- infliximab
what is treatment to maintain remission of UC?
- 5-ASA
* azathioprine, for patients who relapse despite 5-ASA treatment or are ASA intolerant