Jaundice + LFTs Flashcards

1
Q

what blood tests are taken to measure liver function

A
Bilirubin 
Albumin 
Prothrombin Time (PT)
ALP (alkaline phosphatase) 
AST + ALT
GGT
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2
Q

which LFTs measure the livers synthetic function

A

Bilirubin, Albumin, PT

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3
Q

which LFTs demonstrate hepatocellular damage

A

AST + ALT

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4
Q

which LFT is significantly raised in cholestasis

A

ALP

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5
Q

what is bilirubin

A

a normal breakdown product of Haem metabolism

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6
Q

where is bilirubin conjugated

A

the liver

- then excreted via bile into GI tract

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7
Q

what happens to bilirubin that is excreted into GI tract

A

majority egested in faeces as urobilinogen + stercobilin (colours faeces)
roughly 10% is reaborbed into bloodstream + excreted by kidneys

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8
Q

what is jaundice

A

the yellow discolouration of the sclera / skin as a result of hyperbilirubinaemia

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9
Q

what are the three types of jaundice

A

pre-hepatic
hepatic
post-hepatic

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10
Q

what is the mechanism of pre-hepatic jaundice

A

excessive red blood cell breakdown

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11
Q

LFT results pre-hepatic jaundice

A

isolated rise in bilirubin

  • bilirubin is unconjugated as has not undergone conjugation in liver
  • normal AST, ALT, ALP
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12
Q

causes of pre-hepatic jaundice

A

Gilberts syndrome

Haemolytic anaemia

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13
Q

what is Gilberts syndrome

A

autosomal recessive condition causing defective bilirubin conjugation

  • deficiency of UDP glucuronosyltransferase
  • jaundice during illness, fasting, exercise
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14
Q

LFTs in Gilberts syndrome

A

isolated rise unconjugated bilirubin

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15
Q

what is the mechanism of hepatic jaundice

A

dysfunction of hepatic cells

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16
Q

causes of hepatic jaundice

A
alcoholic liver disease
viral hepatitis
autoimmune hepatitis 
medications
haemochromatosis 
hepatocellular carcinoma 
primary sclerosis cholangitis
primary biliary cirrhosis
17
Q

LFT results in hepatic jaundice

A
raised bilirubin (unconjugated + conjugated)
a greater raised ALT/AST than ALP
18
Q

what is the mechanism of post-hepatic jaundice

A

obstruction of biliary drainage – cholestasis

19
Q

causes of post-hepatic jaundice

A

intraluminal - gallstones

mural - cholangiocarcinoma, strictures

extra-mural- pancreatic cancer, lymphoma

20
Q

LFT results in post-hepatic jaundice

A
raised bilirubin (conjugated)
a greater rise in ALP than ALT/AST
21
Q

normal colour of urine + stools suggests which type of jaundice

A

pre-hepatic

22
Q

dark urine + normal colour stools suggests which type of jaundice

23
Q

dark urine + pale stools suggests which type of jaundice

A

post-hepatic

24
Q

what can cause an isolated GGT rise

A

alcohol
phenytoin

(raised GGT + markedly raised ALP = cholestasis)

25
what can cause an isolated rise in ALP
anything that leads to increased bone breakdown: - bony mets / primary bone tumour - vit D deficiency - recent bone fractures - renal osteodystrophy
26
what are the main synthetic functions of the liver
conjugation + elimination of bilirubin synthesis of albumin synthesis of clotting factors Gluconeogenesis
27
how can the synthetic function of the liver be assessed
by measuring: - serum bilirubin - serum albumin - PT time - blood glucose
28
what is the function of albumin
helps to bind water, cations, fatty acids and bilirubin
29
what can cause low albumin
liver disease, e.g. cirrhosis, causing low levels to be produced nephrotic syndrome acute inflammation that causes suppression of livers production
30
what can cause a high albumin
dehydration
31
how does liver dysfunction affect PT time
causes increased PT time due to impaired synthesis of clotting factors
32
common causes of acute hepatocellular injury
poisoning -- paracetamol overdose infection -- hepatitis A + B liver ischaemia
33
what is cholestatic pruritis
generalised itch that occurs with post hepatic jaundice - accumulation of bile salts below skin causes inflammatory response - often worse at night + exacerbated by heat - no sin lesions
34
tx of cholestatic pruritis
mild - topical menthol cream | mod/severe - cholestyramine