Gastroenterology Flashcards
3 major determinants of acid production from the gastric parietal cells
- ACh from parasympathetic pathway
- Gastrin from the antral G cells
- Histamine from the ECL
What responds rapidly to thiamine replacement in wernicke’s encephalopathy?
Ocular palsies are relieved within hours.
Improvement in ataxias, apathy and confusion takes longer.
What medications are absolutely contraindicated with DAA therapy in hepatitis C?
Carbamazepine and amiodarone and rosuvastatin.
Rosuvastatin - increased risk of rhabdomyolysis
Amiodarone and DAA - sudden death
FODMAP diet in IBS
FODMAPs is an acronym (abbreviation) referring to Fermentable Oligosaccharides, Disaccharides, Monosaccharides and Polyols.
Generally food to avoid in IBS are:
- Onions
- Garlic
- High fructose containing food eg beer, juice, most fruits
- Cereals and grains such as wheat
Risk of perinatal HCV transmission?
Breast feeding with HCV positive mother?
How do you check for HCV infection in infant?
2-8%, much lower than HIV/HBV, risk is higher if coinfection with HIV.
Breastfeeding is OK - HCV RNA is detected in breast milk but no increased risk with breast feeding
Test baby by HCV antibody at >15-18 months or use HCV RNA PCR.
HLA associations with coeliacs disease
HLA DQ2
HLA B8
When is liver biopsy indicated in NAFLD?
- Abnormal ALT/GGT <2-3x ULN
- > 3 features of metabolic syndrome (++ waist circumference, increased TGL and decreased HDL, insulin resistance)
Biopsy is especially indicated if feature of metabolic syndrome includes type 2 DM as they have 75% chance of NAFLD.
Mediterranean diet
High in monosaturated fats (olive oil, nuts, avocado), fish and green leafy vegetables.
Low in saturated fats and red meat.
Side effects of PPI
- Pneumonia
- Gastroenteritis - campylobacter, salmonella, C diff
- Osteoporosis
Name 5 contraindications for liver transplant
- Prior or current malignancy except for HCC
- Active infection (exceptions are HBV, HCV, HIV)
- Severe cerebrovascular/cardiovascular disease limiting with poor prognosis
- Alcoholic liver disease with repeated alcohol cessation and poor social circumstances
- Severe metabolic syndrome - OSA, diabetes, HTN, hyperlipidaemia, morbid obesity.
What is the antiviral of choice in HBV/HIV coinfection?
Tenofovir - has both antiviral activity against HIV and HBV.
Surveillance endoscopy for Barrett’s oesophagus depending on degree of dysplasia
No dysplasia - every 3-5 years
Low dysplasia - every 6 months
High grade dysplasia - every 3 months
If high grade dysplasia is found on first endoscopy, likely cancer and needs definitive management
If prevalent, close surveillance or definitive management.
Once high grade dysplasia is identified, can be managed with intensive 3 month screening, RFA, or surgery.
Extrahepatic manifestations of hep C - name 6
- Cryoglobulinaemia
- Lymphoproliferative disorder - NHL, MALT
- Porphyria cutanea tarda
- Sjogrens syndrome
- Diabetes
- Thyroid dysfunction
Affects 40-70% of patients
4 top causes of HCC
- HCV
- Alcohol
- HBV
- NAFLD
Histological findings of eosinophilic oesophagitis
Management
Esophageal eosinophilia as characterized by >25 intraepithelial eos/HPF, basal zone hyperplasia, dilated intercellular spaces.
Management:
- Trial PPI
- SFED 6 weeks
SAAG
SAAG = serum albumin – ascites albumin.
A high gradient (SAAG >1.1 g/dL) indicates portal hypertension and suggests a nonperitoneal cause of ascites:
- Cirrhosis
- CHF
- Nephrotic syndrome
- Protein losing enteropathy
- Portal hypertension
A low gradient (SAAG < 1.1 g/dL) indicates nonportal hypertension and suggests a peritoneal cause of ascites:
- Peritoneal mesothelioma/carcinomatosis
- TB peritonitis
- Sarcoidosis
- SLE
- HSP
- Fungal/parasitic infections
Role of NS5A and NS5B in HCV life cycle.
Name some inhibitors for each.
NS5A - involved in transport from ER to golgi apparatus, therefore involved in viral replication and assembly.
Ledipasvir, Daclatasvir, Ombitasvir.
NS5B - has RNA dependent RNA polymerase involved in viral DNA synthesis.
2 kinds of drug classes exist -
- nucleoside inhibitor which causes chain termination (Sofosbuvir)
- non-nucleoside inhibitor which causes allosteric inhibition (Dasabuvir)
What is the treatment of choice in HBV patient with previous exposure to lamivudine?
Tenofovir.
Increased entecavir resistance upto 30% in patients previously treated lamivudine.
What is the relationship between 6-TGN level and 6-MMP level with TPMT activity?
When are measuring thiopurine metabolites helpful?
6-TGN levels are INVERSELY correlated with TPMT activity.
6-MMP levels are directly correlated with TPMT activity.
Measuring metabolites are only helpful if patients are not responding to standard doses of thiopurine as they clarify the reason for non response (ie, non compliance, under-dosing, TPMT resistance, thiopurine refractory
Diagnosis of coeliac disease
Histology is still gold standard.
Serological diagnosis:
- Anti-tTG IgA and endomysial antibody has highest sn/sp - 95/100, however they are both IgA
- If IgA deficiency, use IgG deaminated anti-gliadin antibody (90/100)
Anti-gliadin antibody is now out of fashion due to above tests having superior sn/sp.
Paracetamol metabolism
90% - metabolised into inactive sulphate and glucuronide conjugates and excreted in the urine
10% - metabolised by CYP P450 (mainly 2E1 and 3A4) and results in formation of NAPQI. This is bound to glutathione and eliminated in the urine.
Toxicity occurs in paracetamol due to glutathione depletion.
Risk factors for variceal bleeding
- Varix size (large - 30% annual risk of bleeding)
- Child Pugh class C>B>A
- Red sign, red wale mark on varix
- Continued ETOH use
- Previous bleed - 60% risk per annum
Indications for qualitative and quantitative HCV RNA PCR.
Qualitative PCR - can detect very low levels of HCV RNA. Indicates presence or absence of RNA. Therefore useful in diagnosis of cure or diagnosis of infection.
Quantitative PCR - quantifies viral burden. Useful in predicting response to interferon and determine the length of treatment with DAA.
Three types of autoimmune hepatitis?
- Type 1 - ANA/SMA positive. Affects both adults and children
- Type 2 - Anti LKM1 (anti-liver, kidney microsomal type 1). Affects children only
- Type 3 - soluble liver-kidney antigen. Affects adults in middle age.
What is the significance of first episode of SBP?
Has 40% overall 1 year survival…
Therefore should trigger a referral for liver transplant if patient is a candidate.
Mechanism of hepatopulmonary syndrome
Significant intrapulmonary capillary vasodilation which leads to:
- Ventilation-perfusion mismatch due to increased blood flow through the pulmonary capillaries in setting of preserved alveolar ventilation, resulting in the passage of mixed venous blood into the pulmonary veins.
- Diffusion-perfusion limitation due to more blood flow through the capillaries which leads to insufficient partial pressure (or driving pressure) of oxygen for oxygenation of blood moving near the center of the alveolar capillary because of the increased diameter of the intrapulmonary capillaries. Giving O2 improves this diffusion gradient and eliminates this physiological shunting.
Why are sodium phosphate enemas contraindicated in older adults?
Associated with complications including hypotension and volume depletion, hyperphosphatemia, hypo- or hyperkalemia, metabolic acidosis, severe hypocalcemia, renal failure, and EKG changes (prolonged QT interval)
4 causes of early (<3/12) liver transplant morbidity/mortality
- Infection - bacterial, CMV, fungal
- Biliary stricture
- Renal/diabetes
- Graft failure (now rare)
CMV/PJP risks are managed with PO valgancyclovir for 3 months and cotrimoxazole for 6 months. Gancyclovir is not used as it is myelosuppressive.
Barrett’s oesophagus treatment
- Life long PPI
- Surveillance endoscopy as per degree of dysplasia
- Endoscopic ablative therapy for dysplasia with RFA
- Manage risk factors - eg obesity, smoking
No benefit from anti-reflux surgery
Primary sclerosing cholangitis
Associated with IBD (75%)
pANCA positive
MRCP shows beading of biliary tree.
If MRCP is normal - may be small duct PSC, and consider biopsy to confirm.
Ursodeoxycholic acid improves LFT.
Increased risk of cancer - check CA19-9 (pancreatic, bile duct cancer)
Factors associated with spontaneous clearance of HCV
- Younger age
- Female
- MHC genes, IL28B
According to the Milan criteria in HCC and liver transplantation, in which situation is it acceptable to transplant?
- Single tumour <5cm
2. No more than 3 tumours with largest less than 3cm in diameter
Name examples of following laxative classes
- Bulk forming
- Osmotic laxatives
- Stimulant laxatives
- Stool softeners
- Bulk forming - psyllium, methylcellulose
- Osmotic laxatives - lactulose, sorbitol, macrogol
- Stimulant laxatives - Senna, bisacodyl
- Stool softeners - bisacodyl, docusate.
What is the benefit of variceal band ligation
- Significant reduction in bleeding at 1 year and 2 year
- There is an actual mortality benefit - significant reduction at 2 years.
Therefore, compared to propranolol, variceal band ligation is much more effective in that it reduces incidence of variceal bleeding as well as reduce mortality.
Autoimmune associations with coeliac disease
- Type 1 DM
- Hypothyroidism
- IgA deficiency
Name 6 contraindications for liver transplantation.
- Pulmonary hypertension >40mmHg
- AIDS responding poorly to HAART
- Multiorgan failure
- Active substance abuse
- Extrahepatic malignant disease
- Severe uncontrolled systemic infection
Primary biliary cirrhosis
ANA/AMA positivity
Presents with fatigue and pruritis
Treat with ursodeoxycholic acid,
Pruritis - cholestyramine, antihistamines, rifampin
Definitive treatment is liver transplant.
Histology will show granulomas with bile duct damage.
Definition of SVR (sustained virological response) in Hep C
Hep C PCR negative 12 weeks after finishing the course of therapy. ie, elimination of reservoir.
Management of alcoholic hepatitis
- Establish disease severity using MELD or MDF scores
- MDF >32, presence of hepatic encephalopathy
- MELD score of >18 - Consider transjugular liver biopsy to confirm diagnosis of alcoholic steatohepatitis
- Treat with prednisolone if high risk, pentoxifylline if steroids are contraindicated or early renal failure
- Reassess response at 7 days to see whether prednisone should continue for 3 more weeks or stop depending on Lillie score
Definition of portal hypertension
As defined by HVPG
HVPG = Wedged hepatic venous pressure - free hepatic venous pressure
> 5 = portal hypertension
Clinically significant PTH is HPVG of >10 which increases the likelihood of clinical decompensation, HCC and variceal formation.
What is the benefit of propranolol in varices management?
Meta-analysis showed reduced bleeding rates vs placebo, however this benefit is seen mainly in medium to large varices, not small varices.
Also reduces risk of 1st variceal bleeding via 50%.
No clear mortality benefit compared to placebo.
Also poorly tolerated - 1/4 do not tolerate it
<40% achieve desired reduction of HPVG.
Causes of hypergastrinaemia
- Prolonged acid inhibition - PPIs, H2RA
- Atrophic gastritis
- Vagotomy/SB resection
- Gastrin secreting tumours
- Renal failure
- Hypercalcaemia
Best test for hypergastrinaemia is fasting gastrin level.
2 types of hepatorenal syndrome
Type 1 - acute deterioration with usually identifiable trigger (sepsis, bleeding etc), potentially reversible with IV albumin and terlipressin. Complicates 25% of SBP.
Type 2 - slow progression/indolent. Annual incidence of 8% in patients with cirrhosis and ascites. Poor outcome without transplant. Often associated with refractory ascites.
What is the significance of HCV genotypes as it relates to interferon and DAA treatment?
Reason for doing genotype testing?
Higher SVR achieved in interferon treatment - 2>3>1b>1a
Higher SVR achieved with DAA treatment 1>3 (as current DAAs are developed to target genotype 1)
Therefore genotype testing is important in that:
- Predicts response to interferon
- Determines duration of treatment with IFN
- Determines which DAA combination to use.
4 risk factors for neonatal vaccination failure in HBV
- eAg positivity
- HBV DNA >10e7
- Intrauterine transmission
- Vaccine escape mutations
Management of HCC in the following:
- Single lesion <3cm
- Upto 3 nodules of less than 3cm in diameter
- Single lesion less than 3cm, with evidence of portal hypertension or raised bilirubin
- Multinodular HCC or portal invasion
1 - Resection
2 and 3 - Liver transplant, or RFA if comorbidities preclude transplantation. All curative intent.
4 - sorafenib. Not curative.
Advantage of IFN over antiviral therapy in HBV
Duration of treatment is shorter - 48 weeks
Good for young patients who might consider pregnancy in the future.
Treatment of NAFLD
- Weight loss!!! and Mediterranean diet
- Treat insulin resistance with metformin
- Reduce fibrosis - Vitamin E has some evidence especially in NON DIABETIC PATIENTS - significant overall histological improvement in NASH at 96 weeks when compared to placebo
- Manage co-factors (Alcohol, HBV, HCV)
King’s college criteria for liver transplant in paracetamol poisoning
What about non-paracetamol related acute liver failure?
Paracetamol related acute liver failure:
pH 7.3 or all of the following:
- INR >6.5
- Hepatic encephalopathy grade 3-4
- Creatinine 300mmol/L
Non-paracetamol related:
INR >6.5 or 3/5 criteria (which I won’t try to remember…)
Cag A positivity in H pylori
More virulent.
Clinically associated with more duodenal ulcers, worse gastritis, higher risk of relapse.
Indications for annual colonoscopy in UC (ie high risk)
If high risk as defined below:
- Stricture in the past 5 years
- Extensive colitis with mod/severe active endoscopic/histologic inflammation
- Dysplasia in the last 5 years AND declining surgery
- PSC
- FmHx of CRC in 1st degree relatives <50
(if family history of IBD and CRC in first degree above age of 50, then screening is 3 yearly)
Pathophysiology of portal hypertension
Cirrhosis leads to intrahepatic resistance with resultant increased splanchnic and systemic vasodilation.
Vasodilation leads to activation of RAA due to relative renal hypoperfusion and intravascular volume depletion with increased , water and renal vasoconstriction.
Sodium retention leads to refractory ascites, water retention leads to hypervolaemic hyponatremia, and renal vasoconstriction leads to HRS.
SBP prophylaxis in cirrhosis
Used in patients at high risk for SBP which includes:
- Patients with cirrhosis and gastrointestinal bleeding.
- Patients who have had one or more episodes of SBP
- Patients with cirrhosis and ascites if the ascitic fluid is 15 g/L along with either impaired renal function or liver failure.
- Patients with cirrhosis who are hospitalized for other reasons and have an ascitic protein concentration of less than 1 g/dL (10 g/L).
If inpatient variceal bleed - use IV ceftriaxone
Otherwise, daily norfloxacin 400mg, cotrimoxazole 960mg (regular dosing preferred as it reduces resistance)
Cardinal feature of achalasia
Management of achalasia
Incomplete LOS relaxation with oesophageal aperistalsis.
Management:
- Surgery - Modified heller myotomy - surgical division of LOS with fundoplication. Good response with response upto 85% at 5 years, mortality 0.3%
- Botulinum toxin - similar efficacy to dilatation but much safer. Median effect of duration 12 months.
- Pneumatic dilatation - perforation 5%, mortality 0.2%, response 65% at 5 years.
In the setting of HBV viremia as detected on HBV DNA PCR, what dose absence of HBeAg mean?
Suggests presence of pre-core HBV mutant or basal core promotor mutant.
Pre-core mutant - eliminates HBeAg production
Basal core promotor mutant - down regulates HBeAg production.
These mutants are associated with increased development of advanced disease (such as cirrhosis, HCC). Makes up around 50% of chronic HBV infection.
What is the treatment for HBV/HDV coinfection?
HBV/HDV coinfection is associated with more severe acute hepatitis and higher mortality. Treat with peg-interferon alpha for at least 48 weeks.
Factors associated with more rapid HBV disease progression
- Male
- Alcohol and smoking
- Older age (longer duration of infection)
- Family history of HCC
- Coinfection with HCV, HDV or HIV
- HBV genotype C (C for cirrhosis)
3 major classifications of causes for vitamin B12 deficiency
- Dietary - eg vegans
- Gastric - pernicious anaemia, atrophic gastritis, gastrectomy
- Small bowel
- Bacterial overgrowth
- Pancreatic insufficiency
- Crohns disease (due to removal of terminal ileum)