Clinical Interpretation Of Abnormal Liver Function Tests Flashcards

1
Q

What are biochemical markers for liver disease?

A
  • *Aminotranserases
  • AST
  • ALT

**Alkaline phosphatase

5’-nucleotidase

**Gamma-glutamyl transpeptidase (GGT)

**Lactate dehydrogenase (LDH)

**Bilirubin

** = most common

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2
Q

What are biosynthetic liver function test enzymes (LFTs)

A

Bilirubin

Prothrombin time (PT/INR) 
- coagulation factors 2/5/7/10

Albumin

Immunoglobulins (IgG/IgM/IgA)

Conjugated bilirubin excretion

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3
Q

Are liver function tests and enzyme levels sensative and specific for certain GI diseases?

A

NO

  • they only work to help narrow down
  • they can be normal in serious illness or elevated in normal liver functions
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4
Q

What are the two common enzyme elevation patterns?

A

1) hepatocellular damage is present
- elevated AST/ALT
- AST, ALT levels will both be higher than alkaline phosphatase
- bilirubin levels VARY (dont look at this)

2) cholestatic process (blockage of the gallbladder)
- elevated bilirubin, alkaline phosphate and CGT
- Alkaline phosphate > AST/ALT levels

3) isolated hyperbilirubinemia
- ONLY elevated bilirubin

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5
Q

What is the R-value?

A

(measured ALT/ upper limit of normal ALT) / (measured alkaline phosphatase/ upper limit of alkaline phosphatase)

Helps narrow stuff down but hardly ever used

If > 5 = hepatocellular injury

If 2-5 = mixed pattern

If <2 = cholestatic injury

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6
Q

ALT vs AST ratios

A

Helps determine potential causes of liver damage

ALT > AST = general hepatitis

AST > ALT = alcoholism or advanced liver cirrhosis

**ALT is found in hepatocyte cytosol

**AST is found in hepatocyte mitochondria

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7
Q

Relationship between alkaline phosphatase and GGT enzyme relationships

A

If alkaline phosphatase and GGT are elevated = biliary issue

  • either obstruction/infection (cholestasis/cholecystis)
  • **total obstruction will not show this though (both enzymes might be normal)

If alkaline phosphatase is elevated but GGT is normal = bone issue

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8
Q

Direct vs indirect bilirubin

A

Direct (conjugated)

  • is water soluble And polar
  • seen in urine
  • already processed new bilirubin
  • is elevated with biliary obstruction or specific hepatocellular diseases

Indirect (unconjugated)

  • is lipid soluble and non-polar
  • not seen in urine, only blood
  • non processed old bilirubin
  • elevated with hemolysis or general hepatic diseases (hepatitis)
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9
Q

What are possible immunoglobulins and auto-antibodies associated with liver diseases?

A

IgG elevation = autoimmune hepatitis (both type 1/2)

IgM elevation = primary biliary cirrhosis

IgA elevation = alcoholic abuse

IgA/M/G elevation = liver cirrhosis

ANA/ASM = auto immune hep type 1

LKM = auto immune hep type 2

AMA = primary biliary cirrhosis

ANCA = primary sclerosing cholangitis

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10
Q

What does ALT/AST levels >500 usually imply?

A

A acute serious hepatocellular necrosis process
-usually viral infection/direct toxin induction or ischemia

alkaline phosphatase and albumin is normal

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11
Q

What does alkaline phosphatase levels >4x normal usually imply?

A

Cholestatis or obstructive disease

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12
Q

What is the normal liver size?

A

7-10 cm for women

  1. 5-12.5cm for men
    * anything higher = hepatomegaly*
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13
Q

Can chronic liver diseases cause gynenomastea in men?

A

Yes

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14
Q

How to tell cholestasis apart from cholecystitis?

A

Cholesystitis will show a fever and leukocytosis On labs

also cholecysttis pain usually presents with Murphy sign

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