EXAM #2: LIVER PATHOLOGY Flashcards
What are the four most common causes of chronic liver disease in US? (List in order of prevalence)
1) Hepatitis C
2) Alcoholic liver disease
3) Non-alcoholic fatty liver disease
4) Hepatitis B
What is meant by hepatocyte integrity?
Membrane integrity of hepatocytes
When damaged, hepatocytes are “leaky”
What are the two classic liver lab tests?
AST
ALT
Finding these enzymes in the serum indicates that there has been damage to the hepatocytes that have made them “leaky”
What three lab tests test hepatocyte function? What happens to these tests with impaired liver function?
1) Serum albumin–decreased
2) Prothrombin time–increased
3) Serum ammonia–increased
What lab tests are associated with obstructed bile flow?
1) ALP
2) 5’-Nucleotidase (5’-NT)
3) GGT
What are the two types of bilirubin? What is the difference between direct and indirect bilirubin?
- Conjugated= Direct, has sugar moieties added and can be excreted
- Unconjugated= Indirect, no sugar moieties
Unconjugated is “indirect” b/c it is an indirect measurement (Total- conjugated= unconjugated)
What is the normal serum total bilirubin level?
0.1-1.2 mg/dL
What are the clinical manifestations of hyperbilirubinemia?
- Jaundice
- Cholestasis= slowing of the flow of bile
How high does the serum bilirubin need to be for there to be clinical symptoms?
Carvenale= greater than 2 mg/dL
Pathoma= greater than 2.5 mg/dL
Outline normal bilirubin metabolism.
1) RBCs are consumed by splenic macrophages
2) Protoporphyrin (from heme) is converted into UNCONJUGATED bilirubin (UCB)
- Heme oxygenase= Biliverdin
- Biliverdin reductase= Unconjugated Bilirubin
3) UCB binds albumin and is carried to the liver
4) In the hepatocyte ER, UCB is CONJUGATED to CB, via Uridine Glucuronyl Transferase (UGT)
5) CB is transferred to bili canaliculi via MDR-2 and MDR-3 transporters to form bile
6) Bile is stored in the gallbladder
7) Bile is released into the duodenum
8) Intestinal flora convert CB to UROBILINOGEN in the bowel
9) Urobilinogen is oxidized to STERCOBILIN and UROBILIN
What enzyme conjugates UCB in the hepatocyte?
UGT, Uridine Glucuronyl Transferase
- Adds one sugar to bilirubin i.e. monoglucuronides
- OR adds 2x sugars to make diglucuronides
(UGT1A1)
What heme degradation product gives stool its color?
Sterocobilin
What heme degradation product gives urine its color?
Urobilin
What is the etiology of hyperbilirubinemia seen in extravascular hemolysis or ineffective erythropoiesis?
- Increased UCB b/c of heme degradation
- UCB overwhelms liver’s ability to conjugate
What is the lab finding in extravascular hemolysis/ ineffective erythropoiesis?
Elevated UCB
What are the clinical features of extravascular hemolysis/ ineffective erythropoiesis?
1) Dark urine due to increased urine UROBILINOGEN
2) Increased risk for pigmented bilirubin gallstones (excess UCB must eventually be converted to CB–hyperaccumulation of which can cause gallstones)
Note that UCB is NOT water soluble and will NOT be in urine
What is the etiology of physiologic jaundice of the newborn?
Newborns have transiently low UGT (UCB–>CB)
What is the lab manifestation in physiologic jaundice of the newborn?
Elevated UCB
What is the clinical manifestation of physiologic jaundice in the newborn?
Possible kernicterus
- UCB is fat soluble
- Deposits in the basal ganglia and causes neurologic deficits/death
How is physiologic jaundice of the newborn treated?
Phototherapy, which makes UCB more water souble
Note that phototherapy does NOT conjugate UCB*
What is the etiology of Gilbert Syndrome?
Mildly low UGT activity due to a promoter mutation
What is the inheritance pattern of Gilbert Syndrome?
Autosomal recessive
What lab finding is associated with Gilbert Syndrome?
Elevated UCB
What are the clinical features associated with Gilbert Syndrome?
1) Predominantly asymptomatic
2) STRESS e.g. severe infection causes hyperbilirubinemia
What is the etiology of Crigler-Najjar Syndrome Type I?
Autosomal recessive absence of UGT
What is the lab finding in Crigler-Najjar Syndrome?
Extremely elevated UCB
What are the clinical manifestations of Crigler-Najjar Syndrome?
Kernicterius that is typically fatal
How does Crigler-Najjar Syndrome Type 2 differ from Type 1?
Type 2=
- AUTOSOMAL DOMINANT with variable penetrance
- Moderate decrease in UGT activity
- Only occasional kernicterus
NOTE that this is TREATED WITH PHENOBARBITAL*
What is the etiology of Dubin-Johnson Syndrome?
Autosomal recessive mutation in MDR-2 transporter that impairs CB transfer to bile canaliculi
What lab finding is associated with Dubin-Johnson Syndrome?
Elevated CB
What are the clinical manifestations of Dubin-Johnson Syndrome?
Dark liver otherwise innocuous
What is Rotor Syndrome?
Autosomal recessive disorder similar to Dubin-Johnson Syndrome, but NO BLACK LIVER
How do you tell the difference between Dubin Johnson Syndrome and Rotor Sydrome?
1) +/- black liver
2) Labs
What labs are characteristic of Dubin-Johnson’s Sydrome?
- Normal urine coproprophyrins (heme proteins)
- Increased isomer I
What labs are characteristic for Rotor Syndrome?
- Increased urine coproprophyrins
- Normal isomer I
What is the etiology of Progressive Familial Intrahepatic Cholestasis (PFIC)?
- Defects in various biliary epithelial transports (transporters that secrete bile components into bile canaliculi)
- Causes cholestasis and failure to thrive
What are the normal components of bile?
1) Bile salts that emulsify fat
2) Cholesterol
3) Lecithin
4) Bilirubin
5) Bicarbonate
What is the specific mutation in PFIC-1?
Defect in the canalicular ATPase
- Cannot shunt bile into canaliculi without ATP
What is the specific mutation in PFIC-2?
Defect in a Bile Salt Export Pump
What is the specific mutation seen in PFIC-3?
Defect in MDR-3 and impairs phosphatidylcholine transport
What is the inheritance pattern for the PFICs?
Autosomal recessive
What are the clinical manifestations of the PFICs?
1) Cholestasis (has a toxic effect on the liver and can cause fibrosis/cirrhosis)
2) Fat malabsorption
3) Fat soluble vitamin deficiency
4) Osteopenia
5) Liver failure
Note that symptoms begin in infancy and progress to cirrhosis within the first decade of life
What are the two most common bile duct obstructions?
1) Gallstones
2) Pancreatic carcinoma
What are the clinical manifestations of bile tract obstruction i.e. obstructive jaundice?
1) Jaundice
2) Steatorrhea w/ malabsorption (no bile for fat emulsification)
3) Dark urine due to BILIRUBINURIA
4) Xanthomas from hypercholesterolemia
5) Pruritis due to increased plasma bile acids
6) Osteoporosis (not absorbing Vitamin D)
7) Bleeding–impaired Vitamin K production
What are the lab findings biliary tract obstruction?
1) Elevated CB
2) Decreased urine urobilinogen
3) Elevated
- ALP
- GGT
- 5-NT
4) Hyperlipidemia
What are the most common causes of cirrhosis?
1) Alcoholic liver disease
2) Viral hepatitis
3) Obesity
Outline the pathogenic progression of cirrhosis. What are the hallmarks of cirrhosis?
- Hepatocyte necrosis leads to:
1) Progressive fibrosis
2) Regenerative hepatocyte nodules
Bands of fibrosis and regenerative nodules are the hallmarks for cirrhosis
What is the mechanism of liver fibrosis?
1) Kupffer Cells secrete factors that cause stellate cells to convert to myofibroblasts
2) Stellate cells/ myofibroblasts secrete TGF-B
3) TGF-B causes fibrosis
What is the definition of micronodular cirrhosis? What type of cirrhosis is this associated with?
Cirrhosis with regenerative nodules less than 3mm
Alcoholic
What is the definition of macronodular cirrhosis? What is macronodular cirrhosis associated with?
Cirrhosis with regenerative nodules greater than 3mm
- Viral hepatitis
- Alpha-1 antitrypsin disease
- Wilson’s Disease
What are the four manifestations of decompensated cirrhosis?
1) Portal HTN
2) Hepatorenal Syndrome
3) Liver Failure
4) Hepatic Encephalopathy
What are the clinical manifestations of portal hypertension?
1) Ascites
2) Congestive splenomegaly/hypersplenism (consumption of RBCs and platelets)
3) Porotsystemic shunts
- Gastro-esophageal varices
- Rectal varices
- Caput medusae
- Ascites
- Hypersplenism
What are the clinical manifestations that result from decreased detoxification in cirrhosis?
1) Hyperammonemia causing:
- Mental status change
- Asterixis
- Coma
2) Reduced liver removal of estrogen/hyperestrinism causing:
- Gynecomastia
- Spider angiomata
- Palmar erythema
- Testicular atrophy
3) Jaundice
What does decreased protein synthesis in cirrhosis lead to?
1) Hypoalbuminemia and edema
2) Coagulopathy b/c of
- Decreased synthesis of clotting factors
- Impaired activation of epoxide reductase (Vitamin K)
What is ascites?
Excess fluid in the peritoneal cavity
What causes ascites?
1) Portal hypertension i.e. liver disease
2) Non-portal hypertension
- TB
- Pancreatitis
- Nephrotic Syndrome
What does SAAG stand for?
Serum-ascites albumin gradient
What does the SAAG help you differentiate?
Portal HTN= SAAG greater than 1.1 g/dL
Non-portal HTN= less than 1.1 g/dL
How much liver function must be lost for a patient to have clinical manifestations of liver failure?
Greater than 80%
What are the major clinical manifestations of hepatic failure?
1) Encephalopathy
2) Coagulopathy
3) Jaundice
4) Multiple organ failure
What is the definition of hyperacute liver failure?
Failure occurs within 7 days of first symptoms of liver dysfunction (jaundice)
What is the definition of acute liver failure?
Failure occurs within 4 weeks of first symptoms of liver dysfunction
What is the definition of subacute liver failure?
Failure occurs within 5-12 weeks of first symptoms of liver dysfunction
What is the definition of chronic liver failure?
Liver failure in the context of decompensated cirrhosis
What is Hepatorenal Syndrome?
Renal failure that occurs in the setting of cirrhosis or fulminant liver failure
What causes renal failure in Hepatorenal Syndrome?
Alteration in blood flow/ tone to the kidney in the face of liver failure
- Vasodilation in periphery
- Vasoconstriction to the kidney
What are the manifestations of Hepatorenal Syndrome?
1) Oliguria/anuria
2) Increased BUN/ Creatinine
3) Low urinary Na+
4) Normal urinary sediment
What is the difference between Type I and Type II Hepatorenal Syndrome?
Type 1= rapidly progressive
Type 2= moderate progression
Strict definitions are based on serum creatinine*
What is Hepatopulmonary Syndrome?
Triad of:
1) Chronic liver disease
2) Hypoexmia
3) Intra-pulmonary vascular dilation
This results in V/Q mismatch–less diffusion of oxygen as blood is shunted rapidly through dilated pulmonary vessels
What mediates Hepatopulmonary Syndrome?
Nitric Oxide
What is Hepatic Encephalopathy?
Hyperammonemia that results in
1) cerebral edema
2) changes in mental status
Mercaptans are also part of the pathophysiology, but their role is poorly understood*
What are the clinical manifestations of Hepatic Encephalopathy?
1) Mental status changes
2) Asterixis (flapping tremor)
3) Coma
What is fulminant Hepatic Failure?
Acute liver failure with massive liver necrosis leading to:
- Hepatic encephalopathy
- Increased PT/INR
