Flashcards in Icterus/HE in small animals Deck (39):
In what form in newly formed unconjugated bilirubin?
insoluble in water, bound to albumin, dissociates from this before entering liver cell
What happens to bilirubin in the liver cell?
Conjugation with glucoronic acid making it water-soluble for excretion in urine (rate limiting step in hepatocyte)
What do bacteria in the lower urinary tract do?
convert bilirubin into urobilinogen --> enterohepatic circulation
Define pre-hepatic icterus
conjugation and uptake of bilirubin into liver overwhelmed
Define hepatic icterus
uptake, conjugation and excretion of bilirubin in hepatocytes overwhelmed
Define post-hepatic icterus
conjugation, excretion and uptake back into liver overwhelmed
What signs might show clinical signs of icterus? 4
GIT signs 4
-vomiting and diarrhoea (common)
-acholic faeces (i.e. white)
Neuo signs of HE 6
-ptyalism (drooling, cats)
Renal signs 6
Pu/PD (insufficient urea to concentrate)
excessively high daytime frequency of urination
slow, painful urination caused by mm spasms of the urethra and bladder
Haematologic signs 6
-anaemia from GIT haemorrhage
-anaemia of chronic disease
DDx for pre-hepatic icterus
Haemolysis (IMHA, babesia infection, toxins - onions, lead , copper)
DDx for hepatic icterus - CAT 6 (in order of likelihood)
-toxins (acetaminophen=paracetamol, aspirin)
DDx for hepatic icterus - DOG 4 (in order of likelihood)
-acute liver disease
DDx for post-hepatic icterus (both dogs and cats) 3
-neoplasia (liver, duodenum, pancreas - i.e. close anatomic proximity)
-cholelithiasis (uncommon in cats/dogs)
How do you differentiate pre-hepatic and hepatic icterus? 2
PCV and TS (Prehepatic: PCV is low, TS normal. Hepatic - PCV usually normal, TS can be low if albumin is low)
How do you differentiate hepatic and post-hepatic icterus?
Imaging (what the bile duct looks like, what's blocking it perhaps, pancreatitis etc.)
Describe the workup for hepatic diseases - 8
-haematology, chemistry profile, UA
-liver function tests
-aspirate effusion, cytology
-liver fine needle aspirate
-fine needle aspirate and culture of bile
-liver biopsy (histology, culture)
What is the most specific liver enzyme?
ALT (increased means increased numbers of hepatocytes are dying)
Where is AST present?
Liver but also the mm and intestines
What is AP and where is it found?
Alkaline phosphatase. Found in biliary duct cells (which are throughout the liver). Isoenzymes of this are cortisol-induced (dogs only) in bone, intestines, liver, placenta etc
Indications for liver failure on biochemistry - 4
(be sure to run a bile acid test as well)
Where are bile acids produced? From what?
in liver from cholesterol
How do bile acids return to the liver after secretion into small intestine?
How do you measure bile acids? When do levels of this change?
Take two measurements:
1st = fasted
Give food then take 2nd measurement
The rate limiting step ins the re-uptake of bile acids from the blood into hepatocytes. Levels are elevated in liver failure and PSS.
What is HE
ammonia and aromatic AA go directly into blood without passing through liver first means the CNS is exposed to shunted gut-derived toxins
Neurologic signs of HE - 5
Signs of urate stone formation 3
dysuria, stranguria and haematuria
Clinical sign of HE
urate stone formation
Pathogenesis of urate stone formation
increased ammonium concentration in blood, decreased ability to convert uric acid to allantoin in the liver --> more urate excreted in urine
Most important diseases causing HE in CATS - 4
acute liver failure (toxic)
PSS (v rare in cats)
Most important diseases causing HE in DOGS - 3
liver failure (acute) - toxic, infectious
liver failure (chronic) - cirrhosis
In hepatic acidosis, how can FFA and Tg be processed by liver? When doesn't this work? Treatment?
-redistribution to other organs via lipoproteins (especially VLDLs)
-doesn't work if diet is protein-deficient. Treatment therefore requires force-feeding (stomach tube) diet which is high in protein.
How do you test for liver function?
bile acids (remember 2 readings). Not liver enzymes as these won't tell you if the whole liver is working.
What are classic biochemistry signs for HE? 3
low glucose and urea, high bile acids (latter confirms hepatic dysfunction)