Exam 2 Flashcards
locations of pathology associated w/ GI symptoms
Primary GI
• Inflammatory +/- infectious
• Neoplasia
• Drug induced
Non-GI
• Metabolic (e.g. hyperthyroidism, DKA, Addison’s)
• Liver failure
• Kidney disease
Pancreatic
• Pancreatitis
• Exocrine pancreatic insufficiency
First Steps in Diagnosing dog or cat w/ GI symptoms
- Minimum data base (CBC/Chem & urinalysis)
- Fecal
- Cats: T4 , FelV/FIV
- Dogs: cortisol +- ACTH stim
- Pancreatic Serum tests
- GI serum tests
Anatomy of the pancreas & enzyme production
o Exocrine • Acinar cells • Secrete: trypsin (protien), pancreatic lipase (fat), pancreatic amylase (carb) o Endocrine • Secretes insulin & glucagon
Stimuli for Pancreatic Secretion
o Acetylcholine from vagus N. stimulates digestive enzymes
o Cholecystokinin (CCK) from GI stimulates digestive enzymes
o Secretin from GI stimulates H2O & bicarb secretion
Diagnosing Pancreatitis
o Inflammatory leukogram: neutrophilia, +- toxic neutrophils,
o +- stress leukogram: lymphopenia
o Erythrocytosis due to dehydration
o Possible anemia due to hemorrhage
o Hyperlipidemia (fatty serum)
o Hyperglycemia
o Azotemia (high nitrogen due to dehydration)
o Increased hepatic enzymes & hyperbilirubinemia
o Electrolyte abnormalities
o May have DIC (increased PT/PTT, increased D dimer, increased FDPs)
o High PLI & TLI
Testing Amylase & Lipase
o Amylase: complex carbs -> maltose and glucose
o Lipase: triglycerides -> fatty acids and glycerol
o in other organs but highest conc. in pancreas & small intestine
o amylase decreased w/ corticosteroid use
o lipase increased w/ corticosteroid use
o inactivated by kidney -> renal disease can cause increased amy/lipase
o Limited diagnostic utility in dogs; suggestive if 3-4X high + no azotemia
o No diagnostic value for cats
Pancreatic Lipase Immunoreactivity (PLI)
o Measurement of serum lipase derived only from the exocrine pancreas
o High Sensitivity and specificity
o Result of tests not affectd by GFR, gastritis, or corticosteroid use
o Magnitude of elevation no correlated w/ prognosis
o Spec or SNAP
Spec PL Vs SNAP PL Vs TLI
- all are biochemical tests that measure presence / conc. of macromolecules in a solution through the use of an antibody or immunoglobulin
- Spec quantitative (numerical conc. of PL)
- SNAP qualitative (normal or abnormal amount of PL)
- TLI decreased w/ EPI, increased w/ acute pancreatitis
Be able to contrast sensitivity and specificity of enzymes detecting muscle injury and pattern of elevation.
- Specificity: increases due specifically to muscle injury
- Sensitivity: increases even if muscle damage is minor
Know what tests you should ask for to detect muscle injury.
- CK
- AST
Know how to differentiate muscle injury from non-muscle disease processes.
- sometimes secondary to other diseases
- Cardiomyopathy -> aortic thromboembolism -> hypoxia of hind limb muscles -> Muscle necrosis -> high CK & AST
Be familiar with other chemistry changes that can be seen with muscle injury.
- Myoglobinuria (urine only tells you blood present; look at other bloodwork to identify hemoglobin, myoglobin, or intact RBCs)
- Hyperkalemia
- Hyperphosphatemia
- Hypocalcemia
Explain the four basic mechanisms that lead to increased serum enzyme activity
Release from damaged cells
- Concentration of enzyme within the cell and/or intracellular distribution,
- enzyme half-life,
- number of cells damaged, severity
Increased production
- Inducers (drugs), neoplasia, hyperplasia, young patient
Decreased removal
- enzymes that are excreted by the kidneys will see increased levels with renal disease
Ingestion or absorption
Correctly select and interpret the enzyme changes used for detection of muscle damage
CK
- Mostly muscle
- Specific, sensitive
- Short half-life
ALT
- Mostly liver
- Not very sensitive for muscle
AST
- Liver or muscle
- Longer half life than CK (rises more slowly than CK)
Understand diagnostic sensitivity and specificity and explain how they influence our interpretation of assay results. Know your equations!
Sensitivity:
- will always detect positives but may falsely identify negatives as positive
- (true pos/(true pos+false neg)) X100
Specificity:
- Will always correctly identify negatives but will sometime incorrectly identify positives as negative
- (true neg/(true neg+false pos)) X100
Understand positive and negative predictive values and prevalence and explain how they influence our interpretation of assay results. Know your equations!
Positive:
- Tells you what % of animals with a positive (abnormal) test result will actually have the disease
- (true pos/(true pos+false pos)) X100
Negative
- Tells you what % of animals with a negative (normal) test actually don’t have the disease
- (true neg/(true neg+false neg)) X100
What are 3 phases of laboratory testing needed to ensure proper quality assurance?
- Pre-analytical: Sampling, transport/sample handling
- Analytical (Instrument measurement)
- Post-analytical: recording & interpreting data
List 5 things that should be included in a quality control program
- Systematic monitoring of equipment operation
- System for monitoring reagent inventory
- Use of controls for external QC on some instruments-results can be plotted in a Levey- Jennings plot
- Written/computerized logs and documentation
- Proper training of ALL instrument users
Identify and be able to discuss hepatic enzyme tests and know which are preferred for small versus large animals.
Small Animals
- ALT – hepatocellular injury
- ALP – cholestasis, isoenzymes
- GGT - cholestasis
Large Animals
- SDH – hepatocellular injury
- AST – hepatocellular injury and muscle injury
- GGT – cholestasis, colostrum
Explain the similarities and differences between hepatocellular disease, biliary disease, and hepatic insufficiency. Identify laboratory data that indicate or suggest the presence of each.
Hepatocellular Dz
- enzymes in organelles/cytoplasm
- enzymes leak out through disruption of membrane
- enzymes in serum increase
Biliary Dz
- enzymes on membrane
- enzymes leak out due to disruption of bile flow
- elevated serum enzymes
Hepatic Insufficiency
- enzymes in organelles/cytoplasm
- too few functional hepatocytes to raise serum enzyme levels
Know the 3 different processes in dogs that produce increased ALP
- Liver ALP:
cholestasis, drugs (dogs) - Bone ALP: bone growth
- Corticosteroids ALP (dogs only)
Understand the explained hepatic function tests and know what test you would want to run in cases with suspected liver disease.
if no icterus, bile acids most important
Total Serum Bilirubin
- Hyperbilirubinemia: rate of bilirubin production exceeds liver’s ability to deal w/ it
- Any bilirubinuria in cats is SIGNIFICANT
Bile Acids
- More sensitive indicator of liver function than bilirubin
- Increase = decreased clearance from portal blood or cholstasis
Blood Ammonia
- Less sensitive than bile acids
- may perform if suspected hepatic encephalopathy
- Increase – portosystemic shunt, significantly decreased liver function, urea toxicosis (cows), ammonia producing bacteria (horses)
Describe hematology or urinalysis abnormalities that may be associated with liver disease.
Hematology
- Mild-moderate anemia
- Target cells, ancanthocytes, microcytosis
Urinalysis
- Bilirubinuria / crystals
- Ammonium biurate crystals
Understand how liver disease can cause increased hepatic enzymes, hypocholesterolemia or hypercholesterolemia, hypoglycemia, decreased BUN, hypoproteinemia with hypoalbuminemia, prolonged coagulation times, and ascites.
Hepatic enzymes:
- shows liver damage because lysis of hepatocytes releases enzymes
Hypoglycemia:
- liver isn’t performing gluconeogenesis
Hypoprotinemia, hypoalbumenia, Hypo/hypercholesterolemia, Decreased BUN
- decreased production by liver due to non functioning hepatocytes
Prolonged coag time:
- decreased production of clotting factors by liver due to non functioning hepatocytes
ascites
- due to portal hypertension
Basics of Liver Failure
- Liver Can’t clear toxins or process ammonia and bilirubin
- Inability to produce proteins, lipids, carbohydrates
- Serum enzymes may not be elevated in end stage
Exocrine Pancreatic Insufficiency (EPI) Basics & Causes
o failure of the acinar cells to produce pancreatic enzymes and HCO3-
o primary or secondary
Causes o destruction of acini, o Deficiency of CCK and secretin, o Deficiency of enterokinase, o Excessive secretion of HCl
Exocrine Pancreatic Insufficiency (EPI) Clinical Signs, Breed Disposition, Diagnosis
o Clinical Signs • Weight loss • Polyphagia • Vomiting • Greasy Ds
o Breeds
• Shepherds
• Collies
o Diagnosis
• Unremarkable CBC/Chem
• TLI is test of choice (TLI is decreased)
• Often occurs w/ SIBO
Tests for GI Disease
o cobalamin o folate o gastrin o carb absorption (horses) o fecal occult blood o Alpha-1 Protease Inhibitor
Serum Cobalamin (B12)
- Requires intrinsic factor to be absorbed in ilium
- Decreased due to Distal small intestinal mucosal disease, EPI, Bacterial overgrowth
- Increased due to B12 supplement
Serum Folate (B9)
- Absorbed in proximal small intestine
- Decreased concentration: Mucosal disease in proximal small intestine
- Increased: SIBO, EPI, B9 supplement
When to evaluate Cobalamin & Folate
- Patients with suspected small intestinal disease (Once EPI & parasites excluded)
- intestinal malabsorptive abnormalities
- bacterial overgrowth
Gastrin Test
- Gastrin stimulates release of HCl in stomach
- Elevated gastrin = vomiting
- elevated due to: Neoplasia, ulcer, obstruction, renal failure, drugs, hepatobiliary dz
Carb Absorption test
- evaluate small intestinal function
- Oral D-xylose and D-glucose absorption test
- Sugar conc. measured at different time intervals
• Decreased absorption = o Delayed gastric emptying o Vomiting o bacterial overgrowth o Rapid intestinal transit o small intestinal dz
Fecal Occult Blood Test
- Identification of small intestinal bleeding by detecting pseukoperoxidase activity of hemoglobin
- very sensitive
- False positives due to Diet, Iron supplementation, Contamination
- A repeatable negative result rules out bleeding into the GI tract
Alpha-1 Protease Inhibitor Test
- Test looks for pathologic protein loss in feces
- Shows protein loss in intestine or blood loss in intestine
- Take 3 fecal samples over 3 days
Bovine GI Content Analysis
o Rumen
• pH > 7 = ruminal alkalosis = decreased microbial fermentation
• pH < 5.5 = ruminal acidosis = carb overload & lactic acid accumulation
o Abomasum
• should have pH ~2-3
• pH can rise due to displacement or parasitisim
Clinical assessment of renal function
o Evaluate creatinine and BUN on serum chemistry (estimation of GFR)
o Evaluate urine specific gravity
o Urinalysis: evaluate proteinuria and sediment changes
How to investigate glomerular function
o urea blood/serum nitrogen (BUN or SUN)
o creatinine
o SDMA
o clearance test
Urea Blood/Serum Nitrogen (BUN)
- Produced in liver from protein metabolism
- Expressed in terms of nitrogen content (BUN)
- More accurate term is serum urea nitrogen (SUN)
- Freely filtered through glomerulus with some tubular resorption
increase in BUN
• decreased GFR
• increased production due to GI bleeding or high protein meals
decreased BUN
• decreased production due to liver dysfunction
• increased excretion due to diuresis
Creatinine
- Freely filtered through glomeruli and not reabsorbed
- better estimate of GFR than BUN
- product of muscle metabolism
- Heavily muscled animals = mildly increased creatinine levels
- Will not significantly increase with muscle damage
- Increases in serum creatinine = Decreased GFR
