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Block 7 - GI > Why am I Yellow? > Flashcards

Flashcards in Why am I Yellow? Deck (24):
1

What is the basic metabolism of bilirubin in the liver?

import across basolateral membrane, conjugation, secretion across apical membrane

2

What are the basic mechanisms behind unconjugated hyperbilirubinemia?

increased input (hemolysis) or decreased output into bile (conjugation defect)

3

What are the basic mechanisms behind unconjugated + conjugated hyperbilirubinemia?

normal input and decreased output (transporter/excretion defect) or increased back flux of bilirubin

4

What is the pre-hepatic mechanism of isolated hyperbilirubinemia?

hemolysis
normal reserve capacity of liver for bilirubin is 7-fold
unconjugated increases and conjugated does not
isolated if no associated liver disease

5

What is the hepatic mechanism of hepatic hyperbilirubinemia?

no associated liver or biliary disease
decreased hepatic conjugation
mild genetic defects (gilberts) are common

6

What are more severe conditions associated with hepatic isolated hyperbilirubinemia?

excretion defects (Crigler Najjar and Dubin-Johnson) - rare

7

What happens in sepsis that causes hyperbilirubinemia?

cytokines alter expression of organic anion transporters for conjugated bilirubin - increase in conjugated transported into circulation with little or no liver inflammation

8

What tests can help determine if hyperbilirubinemia is unconjugated or mixed?

bilirubin fractionation
bilirubin in urine - positive if conjugated elevated and kidney function normal

9

What is the treatment for isolated hyperbilirubinemia?

usually benign
UV light for newborns
transplant for rare patient with severe conjugation defect

10

How can Gilbert's be recognized?

males>females
AD inheritance
serum bilirubin <3-5 mg/dL, increases with fasting and stress

11

What are some exogenous agents causing hepatocyte injury and which have highest aminotransferases (>500)?

viruses*, bacteria, protozoa, helminths
*prescription and non-Rx remedies
metals (iron and copper)
*toxins
alcohol

12

What are some endogenous agents causing hepatocyte injury and which have the highest aminotransferases (>500)?

*ischemia
fat
bile and *biliary obstruction
abnormal misfolded proteins
*Host T lymphocytes

13

How do the measured enzymes differ between necrosis and apoptosis?

aminotransferases raised preferentially in apoptosis
all enzymes released in necrosis

14

What signs and symptoms suggest ischemia induced hepatitis?

dyspnea, edema, cocaine use, summer
heart failure, hypotension, hyperthermia

15

What signs and symptoms suggest obstruction induced hepatitis?

RUQ pain and tenderness

16

When is LD elevated in hepatitis?

elevated when necrosis from ischemia, choledocholithiasis, or acetaminophen toxicity
only modestly elevated in acute viral or autoimmune hepatitis

17

What is the relationship between jaundice and cholestasis?

usually occur together but can have one w/o other
only cholestasis if obstruction not complete or only affects part of liver

18

Which enzymes specifically indicate jaundice vs. cholestasis?

elevated bilirubin vs. elevated alk phos

19

What signs and symptoms suggest cholestasis?

pruritus (itching)
steatorrhea (foul smelling, bulky stools)
night blindness, easy bleeding (fat soluble vitamin deficiency)
increased serum bile acids and lipids (lipoprotein x)
xanthomas

20

What is the mechanism and examples of intra-cellular disorders leading to cholestasis?

interference with secretion of bile contents into cannaliculus
drugs and hormones

21

What is the mechanism and examples of intra-hepatic disorders leading to cholestasis?

obstruction to bile flow by portal infiltration - fibrosis
destruction of bile ducts - PBC (primary biliary cirrhosis), sarcoid granuloma
schistosoma

22

What is the mechanism and examples of extra-hepatic disorders leading to cholestasis?

mechanical obstruction to bile flow
benign stricture, tumors

23

What imaging studies are indicated with cholestasis?

ultrasound initially
precise nature might need cholangiography, ERCP or MRC
extra hepatic causes excluded - biopsy

24

Which autoimmune markers are seen in cholestasis?

Anti-mitochondrial Ab (AMA) in PBC
pANCA in primary sclerosing cholangitis