Chapter 18: Cholestatic Diseases Flashcards
What are functions of bile?
- Emulsify dietary fat in the lumen of the gut via bile salts
- Gets rid of bilirubin, excess cholesterol, xenobiotics, and other wastes that cannot be removed in urine.
Bile deposition in tissue is seen clinically as ________.
Jaundice and icterus = yellow skin and sclera due to ↑ serum bilirubin and other solutes eliminated in bile.
Jaundice occurs due to problems with the metabolism of bilirubin.
How is bilirubin metabolized?
- When time for RBC to be removed => they are consumed by MO of the reticuloendothelial system.
- Broken down into HB (globin + heme)
- => Globin is broken down into AA and recycled
- => Heme => biliverdin via heme oxygenase
- Biliverdin => UCB via biliverdin reductase
- Albumin carriers UCB => liver
- In liver, UCB => CB via UGT (uridine glucuronyl)
NL serum bilirubin and jaundice levels
- NL bilirubin: 0.3-1.2 mg/dL
- Jaundice: > 2-2.5 mg/dL
UCB is not soluble in water and exists mostly bound to albumin. This form cannot be excreted in urine even when blood levels are high. NL, we only have a very small amount of UCB not bound to albumin. what can this UCB do?
Diffuse into tissue, particularly brain in bbs and cause kernicterus.
What can make neonatal jaundice worse?
Breastfeeding
Why does almost every newborn develop neonatal jaundice/physiologic jaundice of the newborn.
We cannot conjugate and excrete bilirubin until about 2 weeks alot, thus, it is NL for almost every newborn to develop transient/mild unconjugated hyperbilirubinemia.
Hemolytic disease of the newborn (erythroblastosis fetalis) results in the accumulation of _________ bilirubin in the brain and can lead to _______.
- Unconjugated bilirubin
- Kernicterus
What are heriditary causes of hyperbilirubinemia?
- Crigler-Najjar syndrome Type I and II
- Gilbert Syndrome
- Dubin- Johnson syndrome
- Rotor syndrome
Crigler-Najjar syndrome type I
Inheritance pattern:
What is defective and how seriously?
Results in:
- Autosomal Recessive
- Complete absence of UGT1A1 activity
- Unconjugated hyperbilirubinemia => child dies as a neonate.
Crigler-Najjar syndrome type II
Inheritance pattern:
What is defective and how seriously?
Results in:
- Autosomal Dominant w/ variable penetrance
- ↓ activity of UGT1A1
- Unconjugated hyperbilirubinemia that is mild with occasional kernicterus
Gilbert Syndrome
Inheritance pattern:
What is defective and how seriously?
Results in:
- AR
- Decreased UGT1A1 activity
- Unconjugated hyperbilirubinemia: mild sx
Dubin-Johnson syndrome
- Inheritance pattern:
- What is defective and how seriously?
- Results in:
- AR
- Mutated canalicular MDR protein 2 (MRP2)
- Impaired excretion of bilirubin glucuronides => Conjugated hyperbilirubinemia => black liver due to pigmented cytoplasmic globules
Rotor syndrome
- Inheritance pattern:
- Defect:
- Results in:
- AR
- Defiency of canalicular membrane transporters
- Conjugated hyperbilirubinemia; inocous
What is cholestasis?
- Extrahepatic/intrahepatic obstruction of bile channels or defects in hepatocyte bile excretion that impairs the formation and flow of bile–> accumulation in the liver parenchyma
*
What are the 2 characteristic lab findings of Cholestasis?
- - ↑ ALP
- - ↑ GGT (gamma-glutamyl transpeptidase)
AST and ALT should be NL.
What are 3 morphological features common to both obstructive and nonobstructive cholestasis?
- Bile pigment in hepatocytes = fine, foamy appearance, with so called “feathery degeneration”
- Long green-brown plugs of bile in dilated bile canaliculi
- If bile canniculi rupture, bile leaves and is phagocytozed by Kupfer cells.
Symptoms of Cholestasis
Treatment
Sx
- Jaundice
- Pruritis
- Skin xanthomasd
- Malabsorption (cannot take up fat-soluble vitamins)
Tx
- Extrahepatic bile obstruction is treated with surgery
- MCC of bile duct obstruction in adults and children
-
Adults:
- Extrahepatic cholelithiasis (gallstones)
- Cancers of the biliary tree or head of the pancreas,
- Strictures resulting from surgery
- Kids:
- Biliary atresia,
- Cystic fibrosis,
- Choledochal cysts,
- Syndromes in which there are insufficient intrahepatic bile
Is changes caused by cholestasis in large bile duct obstruction reversible?
- Intially, yes
- If prolonged => biliary cirrhosis
Inflammation of the bile duct (cholangitis), usually caused by bacteria ascending from its junction with the duodenum that tends to occur if the bile duct is already partially obstructed by gallstones.
Ascending cholangitis
What bugs often cause infection seen in ascending cholangitis?
- Enteric bugs like coliforms and enterococci
Ascending Cholangitis
- Symptoms
- Histological hallmark
- Complications
- Charcots triad: RUQ pain, fever, jaundice (also chills)
- Periductular neutrophils directly in the epithelium and lumen of the bile duct.
- If severe => suppurative cholangitis, which can cause sepsis
What is the most severe form of cholangitis and what is seen?
Why is prompt diagnostic evaluation and intervention imperative?
- Suppurative cholangitis = purulent bile fills bile ducts
- Sepsis rather than cholestasis tends to occur, requiring prompt intervention
What can sometimes become superimposed on the pathogenesis of untreated chronic biliary obstruction and the damage accruing in the liver (i.e., ductular rxns, periportal fibrosis, and hepatic scarrin)?
Can trigger what?
Ascending cholangitis
- Triggering acute-on-chronic liver failure
How can sepsis affect the liver?
Which is most likely to lead to the cholestasis of sepsis?
- Direct effects of intrahepatic bacterial infection (form abscesses and bacterial cholangitis)
- Ischemia related to hypotension caused by sepsis, especially when liver is cirrhotic
- In response to circulating microbial products ***
Response by the liver to circulating microbial products of which kind of organisms is most likely to lead to cholestasis of sepsis?
What is the most common form?
- Gram-negative organisms
- Canalicular cholestasis = bile plugs in centrilobular canaliculi + mild portal inflammation + NO hepatocyte necrosis
What is Biliary Cirrhosis?
Chronic biliary obstruction and ductular reactions that form IRREGULAR, jigsaw puzzle pieces nodules (unlike the usual round nodules seen in cirrhosis).
What is Primary Hepatolithiasis?
Where is is most prevelant?
- Formation of intrahepatic gallstone that leads to
- repeated bouts of ascending cholangitis,
- progressive inflammatory destruction of hepatic parenchyma
- = > increased risk of cholangiocarcinoma
- East Asia
What is the typical presentation of someone with Primary Hepatolithiasis?
- Repeated episodes of ascending cholangitis
- Fever and abdominal pain due to infection of ducts
- Sometimes a mass-like lesions may be present and mistaken for malignancy
Distented intrahepatic bile ducts with pigmented Ca2+ bilirubinate stones in distented intrahepatic bile ducts, with chronic inflammation, mural fibrosis, and peribiliary gland hyperplasia, ALL w/o extrahepatic duct obstruction is characteristic of which disease?
Primary Hepatolithiasis
What is neonatal cholestasis?
When should they seek help?
Prolonged conjugated hyperbilirubinemia in the neonate after two weeks (i.e. not physiological jaundice of the newborn)
Infants w/ jaundice BEYOND 14-21 days after birth
Neonatal infeciton by which virus is a common cause of Neonatal Cholestasis?
CMV
What is a characteristic feature of hepatocytes associated with Neonatal Hepatitis?
Panlobular giant-cell transformation of hepatocytes
What are symptoms of Neonatal Cholestasisi?
- Liver injury/inflammation
- Jaundice, dark urine, light or acholic (grey) poop, hepatomegaly
- There may be varying levels of impaired hepatic synthetic function