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MSS-IHL Exam 1 > IHL I - Bilirubin Metabolism and Excretion > Flashcards

IHL I - Bilirubin Metabolism and Excretion Flashcards

0
Q

senescent RBC

A

after 120 days, picked up by the phagocytes in the spleen

spleen = graveyard for RBCs

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1
Q

what are the components of bile?

A

bilirubin, bile acids/salts, cholesterol

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2
Q

what happens to majority of bile salts?

A

reabsorbed by the liver (95%)

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3
Q

what are the breakdown products of RBCs?

A

globin and heme

globin is catabolized

heme is broken to bilirubin

iron binds to transferrin

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4
Q

bilirubin

A

produced by biliverdin reductase from biliverdin

(biliverdin formed from heme by heme oxygenase)

bilirubin is water-insoluble, unconjugated

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5
Q

what happens to bilirubin after it is synthesized in the macrophage?

A

travels in blood (bound to albumin) to the liver

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6
Q

UDP-GT

A

combines bilirubin with 2x UDP-glucuronic acid to form bilirubin di-glucuronide

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7
Q

glucuronic acid

A

combined with bilirubin by UDP-GT to form bilirubin diglucuronide

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8
Q

what is the fate of bilirubin diglucuronide

A

secreted into the bile through canaliculus and goes to small intestine

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9
Q

hyperbilirubinemia

A

aka jaundice or icterus

high levels of bilirubin in extracellular fluid

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10
Q

stercobilinogen

A

always in the large intestine

excretion form is stercobilin

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11
Q

urobilinogen

A

from stercobilinogen that leaks

goes to liver or kidney

in kidney - converted to urobilin - excreted

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12
Q

heme oxygenase

A

converts heme to biliverdin

release of CO (only place where this happens) > in spleen

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13
Q

kupffer cells

A

macrophage in the liver

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14
Q

biliverdin reductase

A

biliverdin converted to bilirubin

requires NADPH

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15
Q

where is bilirubin formed?

A

in the spleen (NOT liver)

it is water insoluble - transported by albumin to hepatocytes**

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16
Q

what is bile color from?

A

bilirubin

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17
Q

UDG-glucuronyl Transferase

A

converts bilirubin to bilirubin diglucuronide (conjugated or direct)

in the liver

**know this enzyme

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18
Q

indirect

A

unconjugated bilirubin (water insoluble)

19
Q

direct

A

conjugated bilirubin (water soluble)

**bc can react directly

20
Q

clay colored stool

A

liver damage or bile duct obstruction

21
Q

what color stool if bilirubin metabolism pathway defective?

A

clay colored

22
Q

what color is stercobilinogen

A

colorless!

stercobilin is dark brown

23
Q

normal blood level of unconjugated, conjugated, and total bilirubin

A

unconjugated: < 1 mg/dL
conjugated: < 0.2 mg/dL
total: < 1.2 mg/dL

24
Q

jaundice bilirubin level?

A

> 2 mg/dL

25
Q

icterus bilirubin level?

A

> 2.5 mg/dL

26
Q

cholestasis

A

impaired bile flow

increased concentration of bilirubin, bile acids, and cholesterol in blood

27
Q

kernicterus

A

high concentration (15-20mg/dL) bilirubin unconjugated

28
Q

what will hemolytic diseases cause

A

increased indirect bilirubin

- liver cannot handle all of it and you can't break it down
- ex/ G6PD deficiency, pyruvate kinase deficiency, Vit K toxicity
29
Q

pyruvate kinase deficiency?

A

cannot produce ATP in RBCs

-results in hemolytic anemia

30
Q

crigler-najjar syndrome

A

gene for glucuronyl transferase is defective
-cannot conjugate bilirubin

high indirect bilirubin**

bilirubin levels 30-50 mg/dL

31
Q

gilbert syndrome

A

gene for glucuronyl transferase has point mutation

medical student : jaundice that goes away **

indirect bilirubin slightly elevated

under stress causes jaundice

32
Q

Kernicterus

A

in newborn

massive destruction of RBCs
-at birth the glucuronyl transferase is induced

increase in indirect bilirubin

Hb F does not respond to 2,3 BPG

33
Q

increase in direct bilirubin due to?

A

intra or extrahepatic bile duct, gallstone/tumor, defective canalicular transport

34
Q

increase direct and indirect bilirubin

A 
liver malfunction or damage
cirrhosis
alcoholic cirrhosis
hepatitis 
Wilson's disease - Cu problem
35
Q

dubin johnson syndrome

A

black coloration of liver **

increased direct bilirubin

chronic benign

defective canalicular transport

36
Q

rotor syndrome

A

high levels of direct bilirubin

problem with storage of bilirubin in liver cells
-leakage of bilirubin into the blood

multiple defects in hepatocellular uptake and excretion of bilirubin

jaundice, but normal life

37
Q

type I vs. type II crigler-najjar syndrome

A

type I has highest level of unconjugated bilirubin (>20mg/dL)

type I can lead to kernicterus in infancy

38
Q

what disorder results in a glossy black liver?

A

dubin-johnson syndrome

high levels of conjugated bilirubin

39
Q

hereditary disorders of bilirubin metabolism?

A

all recessive

40
Q

what are the two disorders with high unconjugated bilirubin

A

crigler-najjar and gilberts

41
Q

treatment of bilirubin metabolism disorders?

A

no real treatment, but important to be aware

phototherapy in infants

42
Q

what causes prehepatic jaundice?

A

hemolytic processes

43
Q

what causes hepatic jaundice?

A

abnormal liver function
-cannot deal with load of iron

-gilberts, crigler-najjar, dubin-johnson

44
Q

posthepatic jaundice

A

problem with excretion of bilirubin

mechanical obstruction of bile to the intestines
-gallstone or tumor

decreased levels of stercobilin in stool (clay-colored)

45
Q

why do newborns have jaundice?

A

massive destruction Hg F after birth

all this goes to liver, can’t handle it

lots of unconjugated bilirubin

phototherapy given to newborns

46
Q

where does conjugation occur?

A

liver by UDP-GT

makes it water soluble for secretion

MSS-IHL Exam 1 (13 decks)

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