SA Icterus and Hepatic Encepalopathy Flashcards

1
Q

What are the 3 forms of icterus?

A
  • Pre-hepatic (conjugation ad uptake of bilirubin -> liver overwhelmed)
  • Hepatic (uptake, conjugation and excretion in hepatocytes overwhelmed)
  • Post-hepatic (conjugation, excretion and uptake back into liver overwhelmed: CHOLESTASIS)
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2
Q

What IS icterus

A

Hyperbilirubinaemia

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3
Q

Where does the majority of bilirubin come from?

A

Senescent erythrocytes

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4
Q

What is newly formed bilirubin bound to? Why? When does it dissociate?

A
  • Albumin
  • Insoluble in water until conjugated in liver
  • Dissociates before entering hepatocytes
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5
Q

What is bilirubin conjugated with in the liver?

A

Glucuronic acid

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6
Q

What is the rate limiting step of bile production?

A

Conjugation of bilirubin with glucuronic acid -> water soluble for excretion in urine

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7
Q

What are the Ddx for pre-hepatic anaemia?

A

> Haemolysis

  • Babesia
  • IMHA
  • Toxins [Onions, lead, copper]
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8
Q

What history/PE findings indicate liver problems?

A
> GI
- VD+
- Acholic feaces (white, indicates POST-HEPATIC) 
- Melaena (not sure why but commonly associated) 
- Ascites (portal hypertension)
> Neuro (hepatic encepalopathy) 
- Personality change 
- Ptyalism in cats 
- Head pressing 
- Disorintation
- Seizures
- Stupor
> Renal/uro
- PUPD
- Pollakuia (small, freq)
- Stranguria (urgency) 
- Dysuria (difficulty) [ammonium urate crystals]
- Billirubinuria 
> Heamatologic 
- Pale mms (anaemia due to GI haemorhage/chronic diseas [usually mild]/coagulation disorders/haemolysis)
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9
Q

Why are renal signs seen with liver problems

A

Build up of ammonium in blood -> formation of ammonium urate stones -> bloackage

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10
Q

What are he Ddx for hepatic icterus in the cat?

A

> Cat

  • Suparative cholangiohepatitis
  • Lymphocytic plasmacytic hepatitis
  • Hepatic lipidosis (metabolic)
  • Feline infectious peritonitis (viral, young cats, systemic disease)
  • Toxins (Acetaminophen, aspirin)
  • Neoplasiaggyg
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11
Q

What are the Ddx for hepatic icterus in the dog?

A

> dog

  • Acute liver disease (toxins or drugs)
  • Leptospirosis (also -> renal failure)
  • Chronic hepatitis (may not -> icterus as generally long tem end stage liver failure)
  • Neoplasia
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12
Q

What are the Ddx for post-hepatic icterus?

A

> Dogs and cats

  • Pancreatitis -> leakage of enzymes, sever local peritonitis -> blockage of duodenal papilla
  • Neoplasia (liver/duodenum/pancreas)
  • Cholelithiasis (uncommon, usually 2* to cholangiohepatitis)
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13
Q

How would you differentiate between pre-hepatic and hepatic icterus?

A

> Bloods

  • Pre: PCV low, TP normal
  • Hepatic: PCV normal, TP low (if albumen low)
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14
Q

How would you differentiate hepatic and posthepatic icterus?

A

> Imaging

- Ultrasound/contrast radiographs to rule out post-hepatic

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15
Q

What diagnostics can be used to work up hepatic disease once pre- and post- have been ruled out?

A
  • Heam/biochem/UA
  • Liver FUNCTION
  • Coagulation tests (esp important prior to biopsy)
  • Abdo ultasound
  • Aspirate effusion, cytology (ascites)
  • Liver FNA
  • FNA and culture of bile
  • Liver biopsy: histo, culture
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16
Q

What can liver FNA diagnose? What may be needed following this?

A
  • Lymphoma and hepatic lipidosis ONLY
  • No other Dx can be made
  • Require biopsy
17
Q

What do raised liver enzymes indicate?

A
  • Damage to liver cells

- Mostly reversible hepatocyte damage

18
Q

Give 3 liver enzymes that may be used to evaluate liver health. How liver specific are these?

A
  • ALT: liver specific
  • AST: also present in muscle, intestine etc.
  • AP: Specific to biliary duct cells throughout liver BUT isoenzymes may falsely raise levels (cortisol-induced in dogs, bone, intestine, placenta) -> look to see if AP ^ MORE than other liver enzymes, would indicate biliary duct cells affected.
19
Q

What findings on routine biochem and heamatology indicate liver failure?

A
  • low albumen
  • low cholesterol
  • low glucose
  • low BUN (blood urea nitrogen)
20
Q

Which test specifically links to liver function?

A

Bile acids
- produced in liver from cholesterol and recycled in enterohepatic circulation so SHOULD NOT enter systemic circulation.
- If not re-uptaken into liver hepatocytes, congestion in portal vein -> overflow -> ^ bile acids in systemic circulation
> First measurement fasted, then fed, measured post-prandial.
> indicates liver failure OR pss

21
Q

Where should bile be present in the GIT?

A

Released from duodenal papilla

Reuptaken in ileum

22
Q

What 2 substances are the main causes of hepatic encepalopathy?

A
  • NH3
  • Aromatic AAs
    > released in digestion of proteins
    > neurotoxic
    > should be metabolised by liver
    > instead shunted to systemic ciculation and able to cross BBB
23
Q

What are the clinical signs associated with hepatic encepalopathy?

A
> CNS
- Bizarre behaviour
- Head pressing
- Seizures 
- Intermitent blindness 
- Ptyalism in cats 
> Renal/uro
- urate stones -> dysuria, pollakuria, stranguria 
(^ blood ammonium -> decreased ability to convert uric acid -> allantoin in liver -> more urate excreted in urine)
24
Q

Give he 4 most common causes of hepatic encepalopthy in cats

A
  1. acute liver failure (toxic)
  2. Hepatic lipidosis
  3. Neoplasia
  4. PSS (rare in cats)
25
Q

Give the 3 most common causes of hepatic encepalopathy in dogs

A
  1. PSS
  2. Liver failure (acute) - toxins, infections
  3. Liver failure (chronic) - cirrhosis
26
Q

What is the pathogenesis of hepatic lipidosis in cats?

A
  • Starvation -> release of FFAs and TGs
  • Liver would normally B-oxidise or convert to VLDLs to transport in blood BUT starvation means no protein available to carry out either pathway.
  • Lipid gets stuck in liver
27
Q

What protein is required for B oxidation and why?

A

Carnitin requied to transport lipid into mitochondria

28
Q

Why are proteins required to transport VLDLs in he circulation?

A

Otherwise not soluble in blood

29
Q

How is hepatic lipidosis treated?

A

Feed protein -> otfen force feed!

30
Q

Is hepatic lipidosis a 1* or 2* disease?

A

2*

- somethin else caused starvation initially