Gastroenterology Flashcards
2008A Q18
The initial luminal digestion of dietary starch by salivary and pancreatic amylase leads to the formation of which disaccharide?
A. Fructose.
B. Galactose.
C. Glucose.
D. Maltose.
E. Sucrose.
D. Maltose.
Exocrine pancreas insuffiency can be caused by CF, Shwachman-Diamond Syndrome and diabetes.
What enzymes are secreted by the pancreas and what do they digest?
- Trypsin and chymotrypsin - proteins
- Amylase - starch, carbohydrate, glycogen
- Lipase, cholesterol esterase, phospholipase - fats
Describe carbohydrate digestion.
Small digestion by salivary amylase.
Mostly due to pancreatic amylase in small intestine.
Hydrolized to maltase, isomaltase, sucrase and lactase.
Absorbed by brush border.
Describe protein digestion.
Pepsin in stomach degrades protein into peptides.
Trypsin and chymotrypsin continue the digestion in small intestine.
Discribe fat digestion.
Bile salts emulsify fats in the small intestine forming micelles.
Pancreatic lipase and co lipase degrades most of fatty acids.
Further hydrolized by phospholipase and pancreatic cholesterol esterase.
Absorbed in small intestine.
Low ALP, consider ??
Zinc deficiency
Alagille syndrome
Mutation of chromosome 20p
- Pulmonary artery stenosis
- paucity of small intrahepatic ducts
- butterfly vertebrae
- abnormal radius/ulna
- embryotoxin of eye
- characteristic facies - pointed chin, prominent forehead
How should neonatal transmission of Hep B be managed?
- Vaccinate at birth
- VZIG at birth and vaccinate at 6/52, 3/12, and 5/12
- Check HBsAG and anti HBs at 5/12
2-3% don’t respond to vaccinations
2-3% develop Hep B anyway
What does HBeAg indicate?
Present after HBsAg and indicates a high level of infectivity and replication.
What indicates an inactive carrier state in Hep B?
HBeAg negative
Anti HBe Antibody positive
Lower viral load
Normal LFTs
At delivery, what events increase risk for maternal transmission of Hep C
- PROM
- Internal fetal monitoring
Is breastfeeding contraindicated in a mother with Hep C?
No, not contraindicated.
HCV detected in breast milk and colustrum, however, rates of infection are the same b/w breast fed and BMS babies.
What is Wilsons disease?
Difficulty excreting excess absorbed copper from the liver.
Look for raised liver enzymes and reports of decreased performance at school.
Check:
- serum copper
- free ceruloplasmin
- decreased in Wilsons because it is mostly bound to copper. It is the copper carrying protein)
- Urine copper with penicillamine challenge
- Liver copper
- Eye R/V
Gilbert Syndrome
- 2-10% population
- Benign genetic condition
- Mild indirect hyperbilirubinaemia
- Jaundice increased during stress or fasting
- No treatment necessary
Autoimmune Hepatitis (AIH)
Types 1 and 2
Present with malaise, wt loss, anorexia due to cirrhosis, portal HTN
Albumin low, total protein high
Raised immunoglobulins increase the total protein (TP = albumin + globulin)
Diagnosis by serum antibodies, increased aminotransferase, increased protein.
Treat with immunosuppression
- steroids
- azathioprine
Intrahepatic biliary atresia causes……
pale stool and conjugated hyperbilirubinemia
In portal hypertension, you see splenomegally, oesophageal varices and low platelets, but bleeding unlikely.
Why do these signs occur?
In congested liver, blood flow which normal is directed from stomach to liver, is instead directed to spleen which becomes enlarged from excessive blood product breakdown. The only platelets not removed are the very young, sticky platelets which are in such good condition they can prevent bleeds even tho platelets low.
After leaving the spleen, blood flows to the oesaphagus and then back to the heart. This increased flow accumulates in varicose veins causing varices.
In a jaundiced infant, what should you think of? (per gastro exam tips)
Pale stool
Heart murmur
Low GGT
Pale stool = biliary atresia
Heart murmur = Alagilles
Low GGT = Progressive Familial Intrahepatic cholestasis
In teenagers what should you think of for the following (per gastro exam tips)
- Decreasing school performance
- High globulin or any mention of autoimmunity
- Decreasing school performance = wilsons
- High globulin or autoimmunity = Autoimmune hepatitis
In the treatment of chronic Hep C with Ribavirin, what is the most common side effect?
Haemolytic anaemia
What type of virus is HCV?
Single stranded, enveloped RNA
Ribavirin is used in the treatment of acute Hep C infection. What is the most common side effect?
Anaemia
What is the risk of vertical transmission to the neonate is mother is HBsAg +tive and HBeAG positive?
70-90%
What is the risk of vertical transmission to the neonate if mother is HBsAg +tive and HBeAg -tive?
10%
If mother gets an acute Hep B infection during pregancy, what is the risk of transmission to the neonate:
a. in the first trimester?
b. in the third trimester?
a. 10%
b. 80-90%
What managment should apply at birth to the babies of the following mothers?
- HBsAg -
- HBsAg +, HBeAg +
- HBsAg +, HBeAg -
- Unknown
- Routine immunisation
- Hep B vacc and Hep B IG
- Hep B vacc and Hep B IG
- Hep B immunisatin at birth and check HBsAg status
So….any baby with HBsAg positive gets the immunoglobulin
In a a patient with IBD, what other autoimmune conditions should be considered in the context of deranged LFTs?
Autoimmune hepatitis and sclerosing cholangitis.
In autoimmune hepatitis and sclerosing cholangitis, what additional investigations to LFTs would you expect to be deranged?
AIH
ANA/SMA +
LKM + (liver/kidney microsomal antibody)
IgG ++
Normal USS and MRCP
AISC
ANA/SMA +
IgG +
USS and MRCP abnormal
What LFT derangements would you expect to see in a patient with non alcoholic fatty liver disease?
Elevated AST and ALT, typically 2-5 times the upper limit of normal.
AST:ALT ratio <1 (cf etoh liver disease which is >2)
In a faecal analysis what do fat globules and fatty acid crystals indicate?
Fat malabsorption.
Crystals indicate partial hydrolysis.
Common causes included coealiac disease, pancreatic insufficiency, cholestasis, bacterial overgrowth.
What medical conditions have an association with coeliac disease?
- Down syndrome
- Liver disease
- Thyroid disease
- GORD
- IBD
- Menstruation and fertility issues
Which carbohydrates are absorbed by the intestinal sodium glucose transporter SGLT-1?
Glucose
Galactose
What is this disease?
What would be a cause of acute abdominal pain?
Peutz-Jeghers
Often see the peri oral freckling.
Hamartomatous GI polyps with increased risk of malignancy.
Most common cause of acute abdo pain is intussuseption.
Where does iron in ferrous (Fe2+) form usually occur?
Duodenum
What is the hepatic complication associated with IBD? In which is it more common, UC or Crohns?
Sclerosing cholangitis
Much more common in UC
Patients with Alagilles are likely to present with what Vitamin deficiency?
What is the clinical picture?
Vitamin E
Loss of deep tendon reflexes usually the initial finding with subsequent limb ataxia, trunchal ataxia, dysarthria, ophthalmoplegia, nystagmus, decreased proprioception, and decreased vibratory sensation.
Patients with Alagille syndrome prone to vitamin E deficiency because of cholestasis and fat malabsorption.
Severe progressive neurologic disorder. May have cerebellar disease, posterior column dysfunction, retinal disease.
What is intestinal lymphangectasia?
Intestinal lymphangiectasia is associated with
obstruction of the lymphatic drainage of the intestine.
• Lymph which is high in proteins and lymphocytes leaks into the bowel lumen with a resulting protein-losing enteropathy.
• Blood results may show hypoalbuminaemia,
hypogammaglobulinaemia, and lymphocytopaenia.
• There is oedema, fat and fat soluble vitamin
malabsorption and often chylous ascities.
• There are also elevated levels of faecal alpha-1-antitrypsin.
• Treatment involves restricting intake of long-chain triglycerides.
What do fatty acid crystals and fat globules indicate in a stool sample?
Fat globules in the stool indicates fat malabsorption. Fatty acid crystals indicate a problem with mucosal integrity.
Consider Coeliac disease esp if stool positive for reducing sugars.
Which serological test has the best PPV for coeliac disease?
IgA anti-TTG
Sensitivity of the IgA anti-TTG is 61-100%, specificity 86- 100%.
For those <2 years, 10% have absence of IgA anti-TTG, and AGA measurement is advised.
Patterns of LFT abnormalities
Hepatocellular pattern?
Disproportionate elevation in the serum aminotransferases compared with the alkaline phosphatase
- Serum bilirubin may be elevated
- Tests of synthetic function may be abnormal
Cholestatic pattern(Patterns of LFT abnormalities)
- Disproportionate elevation in the alkaline phosphatase compared with the serum aminotransferases
- Serum bilirubin may be elevated
- Tests of synthetic function may be abnormal
Uptodate
AST to ALT ratio
Most causes of hepatocellular injury are associated with an AST that is lower than the ALT. An AST to ALT ratio of 2:1 or greater is suggestive of alcoholic liver disease, particularly in the setting of an elevated gamma-glutamyl transpeptidase
Magnitude of AST and ALT elevations
●Alcoholic fatty liver disease: AST <8 times the upper limit of normal; ALT <5 times the upper limit of normal
●Nonalcoholic fatty liver disease: AST and ALT <4 times the upper limit of normal
●Acute viral hepatitis or toxin-related hepatitis with jaundice: AST and ALT >25 times the upper limit of normal
●Ischemic hepatopathy (ischemic hepatitis, shock liver): AST and ALT >50 times the upper limit of normal (in addition the lactate dehydrogenase is often markedly elevated)
●Chronic hepatitis C virus infection: Wide variability, typically normal to less than twice the upper limit of normal, rarely more than 10 times the upper limit of normal
●Chronic hepatitis B virus infection: Levels fluctuate; the AST and ALT may be normal, though most patients have mild to moderate elevations (approximately twice the upper limit of normal); with exacerbations, levels are more than 10 times the upper limit of normal
Acute liver failure (LFTs)
Acute liver failure is characterized by acute hepatocellular injury with LFTs typically more than 10 times the upper limit of normal, hepatic encephalopathy, and a prolonged prothrombin time.
Marked elevation of LFTs without liver failure
Patients with marked elevations in their liver function tests (approximately 15 times the upper limit of normal or higher) often have acute hepatitis, though in some cases, there may be underlying chronic liver disease (eg, Wilson disease or an acute exacerbation of hepatitis B virus).
AST increased in
acute liver damage, but is also present in red blood cells, and cardiac and skeletal muscle and is therefore not specific to the liver.
ALP is present in
an enzyme in the cells lining the biliary ducts of the liver.
Also present in Bone and Placental tissues.
Gamma glutamyl transpeptidase
more sensitive marker for cholestatic damage than ALP.
In viral hepatitis which test assess the livers synthetic function?
Prothrombin time following parental vitamin k.
●A deficiency of vitamin K, which may be induced by inadequate dietary intake, prolonged obstructive jaundice, intestinal malabsorption, or the administration of antibiotics that alter the gut flora. In such cases, the prothrombin time typically returns to normal within 24 hours after a single parenteral injection of vitamin K. This response is particularly helpful diagnostically when evaluating patients who are jaundiced.
UPTODATE
Dietary issues contribute significantly to the evolution of IDA in infancy and early childhood
■Insufficient iron intake
■Decreased absorption due to poor dietary sources of iron
■Introduction of unmodified cow’s milk (non-formula cow’s milk) before 12 months of age
■Occult blood loss secondary to cow’s milk protein-induced colitis
UPTODATE
Question 35
A patient with pancreatic insufficiency refuses to take enzyme replacement and later presents with renal calculi.
Increased excretion of which one of the following is the most likely cause of calculus formation?
A. Bicarbonate.
B. Cysteine.
C. Oxalate.
D. Phosphate.
E. Urate.
C. Oxalate.
Hyperoxaluria may also be secondary to the increased enteric absorption of oxalate. Fat malabsorption is the most common cause of increased oxalate absorption. The mechanism by which fat malabsorption increases oxalate absorption is via the binding of calcium by free fatty acids in the colon. This decreases the amount of calcium that is available to bind to oxalate and form insoluble calcium oxalate and results in increased oxalate absorption since free oxalate is more easily absorbed compared to calcium-bound oxalate
