Liver Disease Flashcards
Liver accomplishes many things such as
- the synthesis and metabolism of proteins, carbs, and fats
- Production and secretion of bile and vitamin storage.
- dextoxification of metabolic wastes (urea), drugs, and toxins (ammonia, ethanol)
describe the portal vein
-delivers blood from organs of digestion and functions similarly to an artery as it empties into a terminal capillary bed in the liver
while the portal vein delievers __, __, and __ to the liver, the hepatic artery functions to support hepatocytes with __ and ___.
nutrients, drugs, and toxins
oxygen and nutrients
what does the bile duct do?
drains bile from the liver to the gallbladder.
what makes up the portal triad?
portal vein, hepatic artery, bile duct
what is jaundice? and when is it typically visible
- yellow staining of tissue due to deposition of bilirubin
- Typically not visible until serum bilirubin levels exceed 3-4 mg/dL
- first noticed in sclera (also skin, mucous membranes)
causes of hyperbilirubinemia
- conjugated
- unconjugated
- mixed
how is bilirubin produced
- Bilirubin is produced from heme when RBCS are broken down primarily in the spleen= unconjugated or indirect bilirubin
- In the liver, unconjugated bilirubin is conjugated with a glucuronide molecule to form conjugated or direct bilirubin.
Conjugated bilirubin is delivered to the GI tract via the __
biliary duct
what is the difference between indirect and direct hyperbilirubinemia?
- defect causing Hyperbilirubinemia occur before conjugation the patient will manifested with an indirect hyperbilirubinemia.
- if the defect occurs after conjugation, a direct hyperbilirubinemia will result
3 phases of bilirubin metabolism to consider when evaluating jaundice
- Pre-hepatic cause
- hepatic cause
- extra-hepatic causes (aka obstructive or cholestatic jaundice)
what are pre-hepatic causes of jaundice
ex. Excessive hemolysis (e.g. hemolytic anemias), large hematoma
- leads to a pure indirect, unconjugated hyperbilirubinemia
what does hepatic causes of jaundice lead to?
- unconjugated or mixed hyperbilirubinemia: disorders of enzymatic conjugation pathway
ex. Gilbert’s Syndrome
-predominantly conjugated*
what is Gilbert’s syndrome?
-hepatic cause of hyperbilirubinemia
- hereditary, decreased activity of glucuronosyltransferase, an enzyme in the conjugation pathway
- benign, often found incidentally
*most patients have a persistently slightly elevated indirect bilirubin but may increase due to illness, stress, and fasting
hepatic causes of jaundice that lead lead to conjugated hyperbilirubinemia
- Hepatocellular disease (hepatitis):
- Viral infection (HAV, HBV, HCV, others), chronic alcohol use, autoimmune
- Drugs, pregnancy, sepsis, sarcoidosis, others
- Primary biliary cirrhosis
- Primary sclerosing cholangitis
Extra-hepatic (or obstructive or cholestatic jaundice)
causes of jaundice?
- Mechanical obstruction: Gallstones, surgical stricture
- Infection: Often seen in secondary infections with HIV
- Malignancy: Hepatic, metastatic, cholangiocarcinoma, pancreatic
- Pancreatitis
what does extra-hepatic jaundice result in?
conjugated or direct hyperbilirubinemia
associated findings of conjugated hyperbilirubinemia
- Pale stool and dark urine
2. Bilirubin in the urine
associated findings of unconjugated hyperbilirubinemia
- Normal stool and urine color
2. No bilirubin in the urine
what are the aminotransferase (transaminase) and what do they measure
AST, ALT
-they are released into circulation following hepatocellular injurty so they are a measure of liver injury NOT function
ratio of AST: ALT less than 1=
ratio of AST: ALT greater than 2=
Less than 1= viral hepatitis
Greater than 2= alcoholic hepatitis
what is alkaline phosphatase (AP or ALP)?
- present in Kupffer cells, lining the biliary tract
- also present in bone: isoenzymes can be ordered to distinguish source of AP
what can elevated AP or ALP suggest?
- in obstructive biliary disease* 2. may see slight elevations in hepatocellular disease
- Normal in childhood and pregnancy
what is included in a bilirubin panel?
- total
- direct
- indirect
Bilirubin in ___ is ALWAYS a pathologic finding
urine
*Urobilinogen in urine is usually normal, depending on levels
what is Gamma-glutamyl transpeptidase (GGT or GGTP)
- The most sensitive liver enzyme for detecting biliary obstruction
- also very sensitive for cholangitis, cholecystitis
-highest concentrations are found in liver and biliary tract
Elevated GGT and AP = ___
Normal GGT and elevated AP = ____
very likely hepatobiliary disease
skeletal disease, childhood, pregnancy
what is albumin?
- Large protein Synthesized in the liver, thus a true measure of hepatic function
- Long serum half life (12-18 days) so not very useful for acute processes
Hepatocellular disease causes ____ albumin synthesis
decreased
what is prothrombin time (PT or Pro-Time) used for?
- Used to evaluate clotting function
- Since most clotting factors are synthesized in the liver, PT allows indirect assessment of liver function
PT prolongation can suggest ___
hepatocellular or obstructive biliary disease
what lab value can be used to monitor acute changes in liver function
prothrombin time (PT or Pro-Time bc it has a short half-life
-albumin has a long serum half life (12-18 days) so not very useful for acute processes
what are the 3 forms of hepatitis
- viral
- toxic
- autoimmune
describe HepA and its route of transmission
- Highly-contagious, generally sporadic (non-epidemic) caused by a virus
- Fecal-oral transmission
describe the incidence of HepA
- Highly endemic in developing countries
- Contaminated shellfish common source for tourists - In US, infection often linked to: Outbreaks
- Infected food handlers at point of sale
- Certain fresh produce (onions, strawberries)
*Incidence decreasing since targeted use of vaccine in 1995
describe the clinical corse of HepA
- Incubation: LONG (Average: ~25 days)
- Preicteric phase (5-7 days): (sx of viral illness) Abrupt onset fever, malaise, nausea, vomiting, anorexia, abdominal pain, headache. Signs include: hepatomegaly, splenomegaly, bradycardia
- Icteric phase (4-30 days): Conjugated bilirubinuria, followed by pale stools and jaundice (70% of adults)
what is the prognosis of HepA
- in a healthy host: Self-limited, no chronic form of disease
- Rarely associated with fulminant hepatitis, usually only with HCV co-infection
evaluation of HepA
- Evaluation should include: LFTs and hepatitis A,B, and C serology. ALT levels can be very high but do not correlate with disease severity
- Anti HAV IgM: Detectable 5-10 days before symptoms, remains elevated for 4-6 months
- Anti HAV IgG: Present for life, confers immunity
describe why HepA highly contagious
-Viremia and viral shedding proceeds clinical illness thus patients are quite capable of transmitting infection before they are aware of their illness
how is HepB spread?
- Transmitted through blood and other bodily fluids, e.g. semen, saliva
- 100 times more infectious than HIV (HIGHLY CONTAGIOUS)
- Can live in dried blood for up to 1 week
what is the prognosis of viral HepB
90% of infected children progress to chronic disease
-less than 5% of infected adults progress to chronic disease
- Incidence of new infection has declined significantly since vaccine introduced in the early 1980s
- There are still over 1 million cases of chronic HBV infection in the US
risk factors for HepB
- IV drug use
- History of STD
- Health care workers
- Infants of HBV-positive mothers
- Household contacts of HBV-infected persons
- Most commonly child-to-child - Men who have sex with men
- More than one sex partner in a six-month period
First evidence of HBV infection, implies infectivity
HBs-Ag (surface Ag)
Appears after clearance of HBs-Ag or after immunization, implies immunity
Anti-HBs (Ab to HBs-Ag)
antibody to HB core antigen
Anti-HBc