Week 4 - GI Flashcards
What are some CS for liver dz?
anorexia
vomiting
weight loss
weakness
ascites
polyuria
icterus
seizures
melena
polydipsia
grey feces
lethargy
fever
dark urine
obtundation
Why would you get ascites with liver dz?
- hypoalbuminemia, decreased colloidal oncotic pressure
- portal hypertension
Why would you get seizures with liver dz?
hepatic encephalopathy
What are the 5 liver parameters that assess function?
- Albumin
-made exclusively by hepatocytes
-decreased - BUN
-decreased, since the formation of urea is related to the hepatic metabolism of ammonia (liver takes ammonia and makes BUN)
-would be increased with GI bleeding - Glucose
-decreased, reflecting impaired gluconeogenesis - Bilirubin
-might be normal or increased due to cholestasis - Cholesterol
-synthesized by liver, so severe liver dysfunction is
associated with decreased cholesterol synthesis (hypocholesterolemia)
-but with cholestatic dz – would see an increase
Increased liver enzymes tell NOTHING about liver function. What are the liver enzymes?
ALT
AST
ALP
GGT
What’s ALT?
-Alanine aminotransferase (ALT)
-cytosolic
-leakage enzyme – leaks from hepatocytes when cell membrane permeability increases and when the cell undergoes necrosis
-SPECIFIC to liver (small amt in heart, kidneys, muscle)
-t1/2 for dogs: 2.5days (60 hours), so a 50% decrease over 2 to 3 days is a good prognostic sign
-t/12 for cats: 6 hours, MUCH faster, should decrease faster
-anticonvulsants and corticosteroids can cause induction of ALT
-ALT elevation indicates a hepatic abnormality in both species, it provides little information regarding diagnosis, prognosis or appropriate therapy
What’s AST?
-Aspartate aminotransferase (AST)
-not as specific to liver, present in: liver, skeletal muscle, heart, kidneys, brain, plasma
-Serum AST is derived from liver, skeletal muscle, and cardiac muscle sources
-leakage enzyme
-cytosolic and mitochondrial liver isoenzymes
–cytosolic enzyme: released with reversible or irreversible damage to hepatocyte plasma membranes and usually parallels increases in ALT
–mitochondrial liver enzyme: released only with irreversible hepatocyte injury (necrosis)
-t/12 for dogs: 12 hours
-t/12 for cats: 77 minutes
–so AST should return to normal faster than ALT
-if serum AST is much higher than serum ALT, a muscle source of the enzymes should be explored
–usually and increase in AST + CK would mean skeletal muscle damage is playing a bigger factor
What’s ALP?
-Alkaline phosphatase (ALP/AP)
-produced by bile duct epithelium (PRODUCTION enzyme)
-found in liver, bone, intestinal mucosa, kidney, and placenta
–usually never released by other organs, so increased ALP can be specific, particularly in cats (nearly all cats with increased ALP will have liver dz)
–ALP bone isoenzyme increases due to osteoblast activity
-Glucocorticoid-induced isoform in DOGS (not cats)
-Mild increases in feline SAP are significant because cats have only one third the concentration of AP per gram of liver than dogs + shorter t1/2
-t/12 of dogs: 66-72hours
-t/12 of cats: 6hours
-ALP bone isoenzyme can increase with osteoblast activity
What’s GGT?
-Serum gamma-glutamyl transferase (GGT)
-increases due to obstructed bile flow
–most marked elevations in GGT result from diseases of the biliary epithelium, such as
bile-duct obstruction, cholangitis, and cholecystitis
-more sensitive/less specific when compared to ALP for necroinflammatory bile disease
-increases both after administration of glucocorticoids
-GGT»_space; ALP in inflammatory disorders of portal triad and bile ducts
-Both ALP and GGT should always be evaluated concurrently
-in CATS, GGT is more sensitive than ALP for bile dz
**Hepatic Lipidosis: increased ALP, normal-mild increase GGT
**Cholangitis: increased ALP, moderate-marked increased GGT
Why is bilirubinemia ALWAYS ABNORMAL in a cat?
- Higher renal threshold vs. dog - cat is a 9x threshold, so if bilirubin is high, it is truly high
- Cats cannot conjugate bilirubin in PCRT
Why is Increased ALP activity is ALWAYS ABNORMAL in cats?
- No corticosteroid-induced isoenzyme
- Short half-life of ALP (6 hours)
- Less ALP in hepatocytes vs. dogs
Is triaditis more common in dogs or cats?
CATS
liver, pancreas, bowels
Common causes of secondary (reactive) hepatopathies
- Diabetes mellitus
- Hypoxemia
- Hyperlipidemia
- Hyperthyroidism
- GI disease (e.g., IBD)
- Pancreatitis
- Drug-induced
- Right-sided congestive heart failure
What is the Diagnostic Utility of Serum Bile Acids Test?
- Relatively sensitive for diagnosing PSS – 88.9% in dogs
*value of function, so don’t need to run serum BA test if you know liver is already trash
- Improves the diagnostic performance of routine
tests for hepatic disease when used adjunctively - One should perform pre- and post-prandial bile
acid measurements
-BAs under enterohepatic circulation
-BA concentrations provide no information regarding the type or severity of the disease, nor does it differentiate primary from secondary liver disorders
-Serum BA test is not usually indicated w icterus unless you cannot differentiate between pre, hepatic, post
–serum BA test usually more indicated when normal
–NORMAL BAs - prehepatic
–HIGH BAs - hepatic or post
What is the Diagnostic Utility of Blood Ammonia Test?
-marker for liver disease in dogs, particularly
identification of those with HEPATIC ENCEPHALOPATHY due to portal vein vascular anomalies
-ammonia is produced in the GIT, due to microbial degradation of nitrogenous matter in the colon
-ammonia is removed by liver/hepatocytes and converted into BUN
–could be impaired in liver disease or when portal blood does not flow through liver normally
-Blood ammonia in cats is less useful than in dogs, since increases may occur in any disease that produces anorexia
-not routinely done
What are common liver dz in cats?
- Hepatic lipidosis (idiopathic vs. secondary – 26-50%)
- Cholangitis (inflammation of biliary system)/Inflammatory liver dz – 25%
- Neoplasia – 20%
-Hepatic cyst adenomas
-Lymphoma
-Carcinoma
-Mast cell tumor - Secondary reactive hepatopathies – 16%
- Vascular – 6%
- Toxic – 5%
- FIP - < 2%
What is Hepatic Lipidosis?
-accumulation of excess triglycerides in hepatocytes with resulting cholestasis and hepatic
dysfunction
->80% of hepatocytes would be vacuolated
What is the pathogenesis to Hepatic Lipidosis?
-not well understood
-takes up to 6 weeks to see CS
*protein deficiency
* Excessive fatty acid uptake
* Inability to oxidize fatty acids
* Excessive lipogenesis
* Inhibition of synthesis/secretion of very-low-density lipoproteins (VLDLs)
What is the prognosis for Hepatic Lipidosis?
good, improved over years. good outmode with long term enteral feedingprognosis for IHL is influenced to a large
prognosis affected by the ability of the clinician or owner to aggressively meet the cat’s caloric requirements via enteral feeding
poorer prognosis with pancreatitis
What are pre-disposing factors for Hepatic Lipidosis?
obesity
stress
anorexia
Should you restrict protein from a cat with Hepatic Lipidosis?
NO – you should NOT restrict protein from a cat with liver dz (ONLY if it has encephalopathy)
protein is needed for VLDL synthesis, which is already decreased during Hepatic Lipidosis, so help a cat out
How do you DIAGNOSE hepatic lipidosis?
- Signalment and history
- Moderate-marked increase in ALT and ALP
- Moderate increase in serum bilirubin
- Normal to mildly increased GGT
- Enlarged/hyperechoic liver on ultrasound - LIVER BIG AND BRIGHT
- Vacuolar hepatopathy on cytology and histology
-Most affected cats are clinically jaundiced; hence they will have concurrent hyperbilirubinemia.
How do you TREAT Hepatic Lipidosis?
- Food aversion plays important role in anorexia
- Do not force feed the cat!
- Appetite stimulants (benzodiazepines) have limited benefits and may exacerbate the hepatopathy
–benzos can be hepatotoxic - oxepezam, diazepam
–Elura, Mirtazapine, Cyproheptadine - Treat the underlying disease!
- Proactive nutritional and fluid support
- Nasoesophageal feeding tube - temp support of critically ill patient
1. small size, so only liquid diet
2. used in patients that can’t go under GA for other feeding tubes
*Esophagostomy or gastostomy feeding tube - need GA for placement - Avoid feeding orally for first 10-14 days following
tube placement - nothing by mouth
–after 10-14 days, try a novel food and see if cat wants to orally eat, if not, wait another 10-14 days and try again with a diff novel food - Do not restrict dietary fat or protein in cats with HL
- Diets containing 25-40% fat (DM) are well tolerated
Why is ensuring daily energy intake very important in a cat with Hepatic Lipidosis?
-Provision of adequate daily energy intake is the cornerstone of successful medical management
adequate supply of energy is needed to:
1) prevent catabolism of amino acids for energy
2) inhibit peripheral lipolysis
3) avoid excessive energy consumption which will promote hepatic triglyceride accumulation
commercial diets with:
-25-40% fat
-30-45% protein