Test for hepatic, intestinal and pancreatic function and integrity Flashcards
What can you test with the liver?
- Hepatocellular injury =
- damage to hepatocytes leading to leakage of enzymes
- Cholestasis =
- reduced/blocked bile excretion
- release of enzymes induced by retained bile
- Hepatocellular function =
- decreased production or catabolism of substances
- Hepatic portal circulation
- decreased extraction of substances absorbed from the GI
What are liver enzymes?
- ALT = largely liver specific (+muscles also) - small animals
- AST + LDH = liver + muscle
- SDH + GLDH = liver specific in all species - used in large animals (SDH unstable)
(ALP + GGT indicative of liver damage in horses)
What can increase in AST + LDH indicate?
- Can be artefact due to Haemolysis - check serum / plasma quality
What can cause mild increase in AST, LDH +/- ALT?
- Myocyte damage or liver damage - check CK
What are cholestatic enzymes?
- ALP
- GGT
What are the half life of liver enzymes in dogs/cats?
- Days in dogs
- Hours in cats = small increases may be significant
What are components of bile?
- Bilirubin
- Bile acids
- Cholesterol
What are different types of hyperbilirubinaemia?
- Prehepatic = secondary to haemolysis (anaemia)
- Hepatic = due to decreased bilirubin uptake, conjugation and excretion
- Post-hepatic = secondary to obstruction of the extrahepatic bile duct
What can you measure with bilirubin?
- Total bilirubin
- Conjugated bilirubin
What are clinical signs of hyperbilirubinaemia?
- Jaundice - persists for long after liver function returned to normal (due to delta-bilirubin)
What is the function of the liver?
- Detoxification of Body Wastes, Xenobiotics and Drugs
- Synthesis of Plasma Proteins
- Storage of Glycogen, Iron, Copper and Vitamins
- Breakdown of RBC (degradation of haem)
- Synthesis of Cholesterol and Bile Acids
- Production of Clotting Factors
- Removal of Bacteria
- Carbohydrate, Lipid and Amino Acid Metabolism
How can you test hepatocellular function?
- Decreased uptake and excretion of bilirubin and bile acids
- Decreased conversion of ammonia to urea
- Decreased synthesis of metabolites
- Decreased synthesis of coagulation proteins
- Decreased immunologic function
What cause alterations to hepatic blood flow?
- Decreased uptake and excretion of bile acids
- Decreased conversion of ammonia to urea
- Decreased immunologic function
What is the significance of raised ammonia?
When would you get raised ammonia levels?
- Hepatic encephalopathy
- Elevated in -
– Congenital and acquired portosystemic shunts
and liver failure
What can cause increased bile acids?
- Reduced uptake/excretion by hepatocytes
– Reduced hepatocellular mass
– Impaired hepatocyte function - Disruption of enterohepatic circulation
– Portosystemic shunts
– Cholestasis/bile obstruction
What are different SBA tests? (serum bile acids)
- Fasting SBA (>25-30mmol/L = abnormal)
- Post prandial SBA (>25-30mmol/L = abnormal)
What extra hepatic diseases cause elevation in liver enzymes?
- Hypoxia
- GI + pancreatic disease
- Endocrine diseases
- Sepsis
What can you see on haematology of liver disease?
- Microcytosis = (portosystemic shunts or severe liver insufficiency, likely due to altered iron transport or metabolism)
- Ovalocytes = (elliptocytes) are frequently seen in cats with hepatic lipidosis
- Acanthocytes
– lipid disorders
– disruption of normal vasculature (eg, hepatic hemangiosarcoma)
What is seen on urinalysis of liver disease?
- Isosthenuria or inappropriately low USG
- Bilirubinuria (more than 2+ in dogs, any in cats)
- Ammonium biurate crystals or uroliths (40- 70% of patients with portosystemic shunts)
Whats the difference between liver damage and liver function?
- Liver damage = Increased ALT, AST and GLDH
- Decreased Liver function = Increased bilirubin and ammonia, decreased urea and decreased albumin
What is the function of the endocrine pancreas?
- Secrete insulin + glucagon
- Regulate glucose
(2% of pancreas)
What does the exocrine pancreas do?
- Secrete enzymes involved in initial digestion of food
(98% of pancreas)
What are the digestive enzymes secreted by the pancreas?
- Proteases = trypsin, chymotrypsin, elastase
- Lipases
- Amylase
+ bicarbonate
What are tests for exocrine pancreas integrity?
Enzyme assay for amylase + lipase
* Amylase = catalyses hydrolysis of complex starches
(DOGs) - can increase due to decreased GFR
* Lipase = catalyses hydrolysis of triglycerides (can also increase due to decreased GFR)
* DGGR Lipase test
What additional test to DGGR lipase would you want to do to diagnose pancreatitis?
- PLI
- Imaging (ultrasound)
- Fluid analysis
- Biopsy
What are tests for exocrine pancreas function?
- TLI = trypsin-like immunoreactivity
- used in dogs, cats + horses
- detects exocrine pancreatic insufficiency (EPI)
- less useful for pancreatitis
- if serum TLI <2.5ug/L in dogs = EPI
- if serum TLI <8mg/L = EPI in cats
