GI

Question 1

Trichinella spiralis

Answer 1

Nematode (roundworm). Undercooked pork, fox, cat, and bear meats. About 1 wk after ingestion, larvae enter bloodstream and encyst in striated muscle -> muscle inflammation. Trichinosis -> fever, vomiting, nausea, periorbital edema, myalgia. Treat with bendazoles

Question 2

Diverticulosis

Answer 2

False diverticula that involve only mucosa and submucosa. Mostly in Sigmoid colon. Acute diverticulitis -> Inflammation of one or more diverticula, LLQ abdominal pain, marked leukocytosis, iron-deficient microcytic anemia (low hgb and mcv) -> diagnose with CT. Could also be due to carcinoma -> colonoscopy after acute flare up has resolved (6 wks) to rule out malignancy. Treat with ciprofloxacin and metronidazole.

Question 3

Whipple disease

Answer 3

Infection with tropheryma whipplei. Gram +, PAS +. Mneumonic -> Foamy Whipped cream in a CAN. Foamy macrophages in intestinal lamina propria and mesenteric nodes. CAN = cardiac symptoms, arthralgias (joint pain), neurologic symptoms. Diarrhea/steatorrhea later in course of disease. Common in older men.

Question 4

Hemachromatosis

Answer 4

Primary -> AR mutations in HFE gene (chromosome 6). Increased intestinal absorption of iron, increased iron, increased ferritin, decreased TIBC, increased transferrin saturation. Secondary -> due to chronic transfusions (B thal major). Accumulation of iron in liver mostly, also in pancreas, skin, heart, pituitary, joints. Presents >40 y/o when iron levels exceed 20g. Cirrhosis, diabetes, bronze skin, cardiomyopathy, hypogonadism, arthropathy (calcium pyrophosphate deposits). Can cause hepatocellular carcinoma. Treat with phlebotomy or iron chelators (deferasirox, deferoxamine, oral deferiprone)

Question 5

Where does IVC pass through diaphragm?

Answer 5

Central tendon. Mnemonic for where structures pass through diaphragm. I 8 10 EGGs AAT 12 -> IVC = T8, EsophaGus/VaGus = T10, Aorta, Azygos, Thoracic duct = T12

Question 6

Alcoholic hepatitis

Answer 6

AST:ALT ratio > 1.5 with normal alkaline phosphatase level (elevated would suggest biliary obstruction). Metabolic encephalopathy, ascites, edema, mild anemia. Decreased albumin production by liver leads to ascites.

Question 7

Entamoeba histolytica

Answer 7

Transmitted via cysts (fecal oral) in water (lakes, etc.) Presents with bloody diarrhea, abdominal cramps with tenesmus, and pus in stool. Can cause RUQ pain and liver abcesses (more common in right lobe. Infection of colon that seeds the liver via the portal vein). Trophozoites with ingested RBCs on microscopy. Treat with metronidazole followed by paromomycin.

Question 8

Giardia lamblia

Answer 8

Bloating, flatulence, foul smelling diarrhea, and light colored fatty stools. Transmitted via cysts
(fecal oral) in water (often from drinking from freshwater streams/hikers). Teardrop shaped trophozoites with ventral sucking disc or cyst on microscopy (diagnosed by duodenal aspiration). Attach to epithelial cells in duodenal and jejunal crypts through ventral sucking disc. Cause inflammation and villous atrophy which reduces the gut’s absorptive capability. Treated with metronidazole.

Question 9

Location of acetaminophen toxicity

Answer 9

Centrilobar (zone 3) necrosis of liver. Zone 3 has high rate of P450 activity.

Question 10

Chagas disease

Answer 10

Dysphagia (both solids and liquids -> probably neuromuscular rather than obstructive), chest pain, regurgitation. Secondary achalasia (failure of LES to relax due to loss of neurons in myenteric (auerbachs) plexus). Endemic to South America. Caused by Trypanosoma cruzi. Destroys myenteric plexus causing achalasia, megacolon, and megaesophagus. Trypomastigote on blood smear. Treated with Benznidazole or nifurtimox -> Cruzing in my Benz with my Fur coat on.

Question 11

Acute Hepatitis B

Answer 11

Up to 15 wks after exposure, patients positive for HBV DNA, HBsAg, anti-HBcAb, and HBeAg. Negative for anti HBeAb and anti-HBsAb. Presents with fatigue, myalgia, nausea, abdominal pain, jaundice, RUQ tenderness. Treated with tenofovir (adenosine analog inhibits reverse transcription) and interferon alpha (blocks viral replication)

Question 12

Yellow fever

Answer 12

Mosquito borne ssRNA virus (flavivirus). Often presents with jaundice, aching pain, high fever, and Faget sign -> fever with bradycardia. Leukopenia present in early phases with elevation of transaminases (asp > ala from viral damage to myocytes as well as hepatic cells) and direct bilirubin. Eosinophilic degeneration with condensed nuclear chromatin (Councilman bodies). Zone 2 of liver most commonly affected

Question 13

Gap Lactic acidosis

Answer 13

Can be caused by acute ethanol intoxication -> elevated NADH:NAD ratio favors conversion of pyruvate to lactate. Leads to high lactate and limits pyruvate available for gluconeogenesis leading to hypoglycemia. Patient compensates for metabolic acidosis by breathing faster leading to tachypnea.

Question 14

MOA for Cholera toxin

Answer 14

ADP-ribosylates the Gs-alpha subunit. This activates adenylyl cyclase but cannot hydrolyze the bound GTP to GDP -> continuous activation of PKA. PKA phosphorylates CFTR which increases Cl- excretion leading to H2O efflux and “rice-water” diarrhea. V. cholerae is non-lactose fermenting and oxidase positive

Question 15

Hemolytic-uremic syndrome

Answer 15

life threatening condition associated with infection by E. coli O157:H7 (EHEC) (generally associated with consumption of undercooked meat). HUS is characterized by anemia, thrombocytopenia, and elevated creatinine, indicating renal failure. Caused by Shiga-like toxin which inactivates ribosomes causing cell death. This leads to sloughing off of epithelial cells in gut leading to bleeding. Microthrombi forming on damaged endothelium -> mechanical hemolysis (schistocytes on peripheral blood smear). Platelet consumption and decreased RBF

Question 16

H. pylori histology

Answer 16

punched-out solitary lesions with underlying tissue replaced with chronic inflammatory cells. Regular, sharply demarcated borders, and a smooth base filled with exudate.

Question 17

Metastatic carcinoid syndrome

Answer 17

Neuroendocrine cell tumor with prominent rosettes. Releases vasoactive amines (5-HT, histamine, gastrin, etc). Intestinal tumors are asymptomatic because the liver metabolizes these vasoactive amines. Primary tumor usually in ileocecal junction. Once there are mets to the liver, this metabolism doesn’t occur leading to fatigue, chest tightness, shortness of breath (5-HT causes tricuspid/pulm valve fibrosis), nausea and diarrhea (gastrin) and flushing of skin (histamine)

Question 18

Pancreatic adenocarcinoma

Answer 18

Presents with weight loss, jaundice, epigastric pain radiating to back. May also have signs of DVT -> migratory thrombophlebitis called Trousseau syndrome (thrombi appear and disappear in various parts of body due to hypercoaguable state). Labs show increased amylase, lipase, and alk phos. Tumor markers such as CA19-9 and carcinoembryonic antigen can be elevated. Associated with smoking, diabetes, and chronic pancreatitis. Surgical removal is only treatment.

Question 19

Primary sclerosing cholangitis

Answer 19

Associated with UC. Jaundice, knee pain, increased alk phos. Inflammation and fibrosis of the intra and extrahepatic bile ducts. Increased risk of cholangiocarcinoma. Liver transplant is the only treatment.

Question 20

VIPoma

Answer 20

Tumor, typically in tail of pancreas, which secretes vasoactive intestinal peptide. Increased secretion of water and electrolytes, and relaxation of intestinal smooth muscle and sphincters. Inhibits gastric acid secretion (hypochlorhydria) leading to increased plasma chloride levels. Causes profuse watery diarrheas, weakness, and lethargy. Verner-Morrison syndrome or WDHA (watery diarrhea, hypokalemia, and achlorhydria). Can be metastatic. Treated with octreotide (somatostatin analog that opposes actions of VIP) and sometimes surgical resection.

Question 21

primary biliary cholangitis

Answer 21

Chronic autoimmune liver disorder. Manifests with itching, fatigue, vitiligo, eczema, hepatomegaly, and xanthomas (sign of hypercholesterolemia). Jaundice can occur in late stage disease. Inflammatory autoimmune attack of small intrahepatic bile duct cells leading to cholestasis. Causes biliary cholesterol to leak into plasma in an abnormal particle (lipoprotein-X) which is cholesterol rich. High antimitochondrial antibodies.

Question 22

Schistosomiasis

Answer 22

Parasitic disease caused by Schistomsoma mansoni. Found in freshwaters of South America. settles in portal/intestinal vasculature. May see diarrhea/dysentery several weeks after infection. May have fever or other signs of systemic infection. Parasites cause local fibrosis and granuloma formation. Chronic infection can cause cirrhosis and portal hypertension. Can also see hepatosplenomegaly, ascites, and esophageal varices. Treatment is with a single oral dose of praziquantel.

Question 23

HLA-B27

Answer 23

PAIR. Psoriasis, ankylosing spondylitis, IBD, and Reiter syndrome

Question 24

HLA-DR3

Answer 24

Type 1 diabetes, SLE, graves disease, hashimoto thyroiditis, Addison disease

Question 25

HLA-DR2

Answer 25

MS, hay fever, SLE, Goodpasture syndrome

Question 26

HLA-DR4

Answer 26

Rheumatoid arthritis, type 1 diabetes, addison disease

Question 27

HLA-DR5

Answer 27

Pernicious anemia, Hashimoto thyroiditis

Question 28

Reye Syndrome

Answer 28

Childhood hepatic encephalopathy. Associated with giving aspirin or other salicylates to children with viral infections (VZV/Flu). Aspirin metabolites decrease beta-oxidation causing mitochondrial dysfunction. Findings: mitochondrial abnormalities, fatty liver, hypoglycemia, vomiting, hepatomegaly, seizures, coma, liver failure.

Question 29

Serratia marcescens

Answer 29

Common cause of nosocomial UTIs. Some strains produce a red pigment on culture. GNR, facultative anaerobe.

Question 30

Echinococcus granulosus

Answer 30

Parasitic tapeworm transmitted by feces of animals such as dogs, wallabies, and kangaroos. RUQ pain, nausea, vomiting. Can cause liver cysts. Exposure of cysts to immune system can cause anaphylactic shock. Treat with albendazole (inhibits tubule polymerization in the tapeworm). Albendazole can causes abnormal liver function tests, cytopenias, and renal failure. If cysts >5 cm you may need to drain + albendazole.

Question 31

Crigler-Najjar syndrome

Answer 31

Type 1 = AR disorder characterized by unconjugated hyperbilirubinemia that is usually fatal within first 18 months of life secondary to kernicterus (increased lethargy and high pitched cry). Mutations in uridine diphosphate-glucuronosyltransferase (UGT1) -> enzyme that conjugates bilirubin with glucuronic acid. Mutations that have >20% activity is called Gilbert syndrome

Question 32

Milk alkali syndrome

Answer 32

Hypercalcemia, metabolic alkalosis, and renal insufficiency. Hypercalcemia can cause fatigue, muscle weakness, depressed mood, and constipation. High Ca, low K, low phosphate. High Ca suppresses parathyroid hormone causing retention of bicarb and metabolic acidosis. Low K is because K is excreted in exchange for H+ as the body attempts to drop pH. Can be caused by antacids, particularly calcium carbonate.

Question 33

Drugs leading to C. Diff

Answer 33

clindamycin, ampicillin, cephalosporins, FQs

Question 34

Vitamin A Deficiency

Answer 34

Night blindness (poor vision in low light), dry conjunctivae, gray plaques, and later development of corneal ulceration and necrosis leading to perforation and blindness. Usually seen in children/pregnant women with diets low in vit A. Also can be associated with malabsorptive diseases. Vit A is absorbed in the duodenum in micelles from bile salts.

Question 35

Treatment of Hep C and side effect profiles

Answer 35

Currently it is Ledipasvir/sofosbuvir for 8-12 wks (side effects: fatigue, nausea, vomiting, diarrhea, and insomnia). Used to be treated with pegylated interferon alpha (side effects: flu-like reaction, depression, and suicidality) and ribavirin (SE: hemolytic anemia, pruritus, asthenia, headaches, insomnia, anorexia, N/V, diarrhea).

Question 36

Pompe disease

Answer 36

glycogen storage disease type II. AR disease with deficiency or defect in lysosomal alpha-1,4-glucosidase. Glycogen accumulates in cytoplasm and lysosomes in heart, skeletal muscle, brain, and liver. Infants rarely survive past infancy and suffer from hypotonia and congestive heart failure. Cardiomegaly, hypertrophic cardiomyopathy, hypotonia, exercise intolerance.

Question 37

Azathioprine

Answer 37

Antimetabolite precursor of 6-mercaptopurine which is used for RA, Crohn’s, UC, glomerulonephritis and other autoimmune conditions. Inhibits lymphocyte proliferation by blocking nucleotide synthesis. Can cause pancytopenia

Question 38

Chronic granulomatous disease

Answer 38

Defect of NADPH oxidase. X-linked recessive. Decreased ROS and decreased respiratory burst in neutrophils. Neutrophils are unable to completely eradicate phagocytosed bacteria and fungi. Leads to inflammatory response often with chronic gut inflammation. Increased sensitivity to catalase positive organisms. Abnormal dihydrorhodamine test (decreased green fluorescence) and nitroblue tetrazolium dye reduction tests fails to turn blue.

Question 39

MOA of fibrates

Answer 39

Decrease levels of VLDL and slightly reduce LDL while mostly dropping triglyceride levels. Fibrates activate the nuclear transcription factor peroxisome proliferator-activated receptor alpha (PPARa) which increases lipoprotein TG lysis via lipoprotein lipase and increases HDL levels.

Question 40

MOA of ezetimibe

Answer 40

Lowers LDL cholesterol levels (typically used in conjunction with statins) by inhibiting cholesterol absorption

Question 41

MOA of niacin for cholesterol/TG therapy

Answer 41

INhibits lipolysis by hormone-sensitive lipase. Leads to reduction in transport of FFAs to the liver and therefore drops TG synthesis. Targeted therapy for reducing triglyceride levels. Can cause flushing, hypotension, and gout exacerbation.

Question 42

Type A gastritis/Type B gastritis

Answer 42

Affects fundus and body but spares antrum. CD4 T helper cells directed and antibodies directed against parietal cells (specifically the H+-K+ ATPase). Associated with other autoimmune diseases such as autoimmune thyroiditis. Can cause increased in gastrin levels leading to mucosal atrophy and intestinal metaplasia. Causes epigastric discomfort and nausea. May cause pernicious anemia. Type B is typically H. pylori associated and preferentially affects antrum

Question 43

External hemorrhoids

Answer 43

Below the pectinate line - somatic innervation and are therefore painful. Less likely to present with rectal bleeding than internal hemorrhoids. Conditions that increase intraabdominal pressure are associated (pregnancy, chronic constipation, heavy weight lifting, etc.). Venous drainage is from inferior rectal vein -> internal pudendal vein -> internal iliac vein -> IVC

Question 44

Intessusception

Answer 44

telescoping of one segment of the bowel into another causing obstruction. Most common 1-5 yrs of age. Sudden, intermittent pain (due to partial reversal of obstruction when bowel stops contracting), possibly vomiting. Can cause currant jelly stool and a sausage shaped RUQ mass. Most commonly near ileocecal junction. Medical emergency -> air enema is used for both diagnosis and treatment. Commonly associated with tumors, recent viral infections (Peyer patch hypertrophy) and Meckel diverticulum but most are idiopathic.

Question 45

Mechanism of action:

1. macrolides (azithromycin, clarithromycin, erythromycin
2. aminoglycosides/tetracyclines
3. Metronidazole
4. Sulfonamides
5. Clindamycin

Answer 45

1. Inhibition of translocation step of protein synthesis by blocking translocation via binding to the 23S rRNA of the 50S subunit (macroslides)
2. Block 30S ribosomal subunit
3. Generation of toxic metabolites (free radicals)
4. Inhibit synthesis of folic acid (B9). Sulfamethoxazole (SMX) particularly inhibits dihyropteroate synthase to prevent folate synthesis.
5. Blocks peptide transfer at 50S subunit (binds 23S subunit but this isn’t its MOA)

Question 46

Hereditary nonpolypsis colon cancer

Answer 46

Also called Lynch syndrome. AD mutation of DNA mismatch repair genes (ex. MLH1) with subsequent microsatellite instability. About 80% progress to colorectal cancer -> proximal colon is always involved. Also associated with endometrial, ovarian, and skin cancers

Question 47

Toxic megacolon

Answer 47

Severe abdominal pain, visibly distended colon on plain film, fever, tachycardia, absent bowel sounds, and “thumbprinting” of bowel on plain film. Predisposing factors: C diff infection, loperamide use (particularly in young children and in dysenteric and enteroinvasive diarrhea), and UC.

Question 48

Aflatoxin B1

Answer 48

toxin produced by Aspergillus flavus fungus. Causes hepatocellular carcinoma