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Questions and Answers
What primarily reflects liver injury as indicated by serum GLDH activity?
What primarily reflects liver injury as indicated by serum GLDH activity?
Increased GLDH activity is a specific marker of the cause of liver injury.
Increased GLDH activity is a specific marker of the cause of liver injury.
False
What is the half-life of GLDH in dogs?
What is the half-life of GLDH in dogs?
8 hours
SDH is considered to be a liver-specific enzyme due to its high concentrations in _______.
SDH is considered to be a liver-specific enzyme due to its high concentrations in _______.
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Which enzyme catalyzes the conversion of fructose to sorbitol?
Which enzyme catalyzes the conversion of fructose to sorbitol?
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Cholestasis is associated with decreased levels of Alkaline Phosphatase (ALP).
Cholestasis is associated with decreased levels of Alkaline Phosphatase (ALP).
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Match the following enzymes with their half-life in dogs:
Match the following enzymes with their half-life in dogs:
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The half-life of SDH in the dog is approximately _______ hours.
The half-life of SDH in the dog is approximately _______ hours.
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What is the normal recovery time for CK activity after acute muscle injury in horses?
What is the normal recovery time for CK activity after acute muscle injury in horses?
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AST activity decreases more rapidly than CK activity after muscle injury.
AST activity decreases more rapidly than CK activity after muscle injury.
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What enzyme is released into the plasma following skeletal muscle injury?
What enzyme is released into the plasma following skeletal muscle injury?
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Haemolysis will cause a false increase in CK activity due to the contribution of constituents within red blood cells or in their __________.
Haemolysis will cause a false increase in CK activity due to the contribution of constituents within red blood cells or in their __________.
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Which condition does NOT typically result in high CK activity?
Which condition does NOT typically result in high CK activity?
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Match the following terms with their descriptions:
Match the following terms with their descriptions:
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Increased CK levels in young puppies are four times higher than adult levels.
Increased CK levels in young puppies are four times higher than adult levels.
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List one physiological factor that may lead to increased CK activity.
List one physiological factor that may lead to increased CK activity.
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What condition can lead to an increase in alkaline phosphatase (ALP) activity in dogs up to 22,000 U/L?
What condition can lead to an increase in alkaline phosphatase (ALP) activity in dogs up to 22,000 U/L?
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Elevated Gamma Glutamyl Transferase (GGT) levels primarily originate from the pancreas.
Elevated Gamma Glutamyl Transferase (GGT) levels primarily originate from the pancreas.
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What is commonly observed in dogs with osteosarcoma regarding ALP serum activity?
What is commonly observed in dogs with osteosarcoma regarding ALP serum activity?
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In cases of primary and secondary hyperparathyroidism, total serum ALP may increase due to the _____ isoform.
In cases of primary and secondary hyperparathyroidism, total serum ALP may increase due to the _____ isoform.
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Match the following conditions with their effect on ALP activity:
Match the following conditions with their effect on ALP activity:
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Which enzyme is mainly used as a sensitive indicator of cholestasis?
Which enzyme is mainly used as a sensitive indicator of cholestasis?
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Which of the following is considered a major acute phase protein (APP) in dogs?
Which of the following is considered a major acute phase protein (APP) in dogs?
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GGT is primarily shed into the blood from the kidney.
GGT is primarily shed into the blood from the kidney.
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What metabolic process is GGT primarily involved in?
What metabolic process is GGT primarily involved in?
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Positive acute phase proteins (APPs) increase in concentration during acute inflammation.
Positive acute phase proteins (APPs) increase in concentration during acute inflammation.
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What is the primary method used to measure total protein concentration in veterinary diagnostics?
What is the primary method used to measure total protein concentration in veterinary diagnostics?
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In cats, serum amyloid A (SAA) is a major APP, while ___ is a moderate APP.
In cats, serum amyloid A (SAA) is a major APP, while ___ is a moderate APP.
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Match the following species with their corresponding major and moderate acute phase proteins:
Match the following species with their corresponding major and moderate acute phase proteins:
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Which cytokine is NOT part of the acute phase response?
Which cytokine is NOT part of the acute phase response?
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The refractometry method in veterinary diagnostics provides an estimate of ___ concentration.
The refractometry method in veterinary diagnostics provides an estimate of ___ concentration.
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Fibrinogen is considered a major acute phase protein in horses.
Fibrinogen is considered a major acute phase protein in horses.
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Which of the following conditions can lead to malabsorption in the small intestine?
Which of the following conditions can lead to malabsorption in the small intestine?
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Increased renal retention of electrolytes occurs in healthy individuals.
Increased renal retention of electrolytes occurs in healthy individuals.
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What is the primary role of electrolytes in the body?
What is the primary role of electrolytes in the body?
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In health, ECF is relatively rich in _____ and _____ but poor in K+, Ca2+, PO4, and Mg2+.
In health, ECF is relatively rich in _____ and _____ but poor in K+, Ca2+, PO4, and Mg2+.
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Match the following electrolytes with their primary locations:
Match the following electrolytes with their primary locations:
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Which condition is associated with unexpectedly high or prolonged peak concentrations of glucose?
Which condition is associated with unexpectedly high or prolonged peak concentrations of glucose?
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What are the four processes that affect serum concentrations of electrolytes?
What are the four processes that affect serum concentrations of electrolytes?
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Electrolytes enter the body only through oral intake of food or fluids.
Electrolytes enter the body only through oral intake of food or fluids.
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What is the primary hormone that affects renal potassium excretion?
What is the primary hormone that affects renal potassium excretion?
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Hypokalaemia occurs when the serum potassium concentration is greater than 5.1 mmol/L.
Hypokalaemia occurs when the serum potassium concentration is greater than 5.1 mmol/L.
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What is the reference interval for normal serum potassium concentration?
What is the reference interval for normal serum potassium concentration?
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A serum potassium concentration exceeding _____ mmol/L is considered life-threatening.
A serum potassium concentration exceeding _____ mmol/L is considered life-threatening.
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Which of the following conditions can cause hypokalaemia?
Which of the following conditions can cause hypokalaemia?
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Match the following potassium conditions with their characteristics:
Match the following potassium conditions with their characteristics:
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A decrease in potassium intake is usually the sole cause of hypokalaemia.
A decrease in potassium intake is usually the sole cause of hypokalaemia.
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What effect do insulin and β2-adrenergic catecholamines have on potassium levels?
What effect do insulin and β2-adrenergic catecholamines have on potassium levels?
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Study Notes
Clinical Biochemistry - Clinical Pathology 410
- Course covers clinical enzymology, including the introduction to enzymology, explaining how different organs, tissues, or cells contain different enzymes. Some enzymes are specific to particular tissues, making them diagnostically helpful. Increased serum enzyme activity suggests either cell injury or increased enzyme production.
- Enzymes catalyze biochemical reactions, converting a substrate into a product. Enzyme activity is directly proportional to its concentration, measured in units per liter (U/L).
- Leakage enzymes are released when cell injury alters cell membranes, while induced enzymes result from increased production stimulated by a stimulus.
- Enzyme half-life influences how long enzyme activity persists in the blood after leakage or induction.
- Tissue specificity of enzymes helps determine the source of tissue injury or stimulation.
- Proper handling and storage are essential for accurate serum enzyme assay results.
Enzymes and Serum Activity
- Increased serum enzyme activity results from leakage or induction. Leakage occurs when cell injury causes membrane damage, while induction involves increased production of an enzyme in response to a stimulus.
- Leakage enzymes pass into the extracellular space and then into the serum.
- Figures 1 and 2 in the text illustrate the mechanisms of leakage and induced enzyme release.
- Various serum enzyme assays are used; accurate interpretation depends on proper handling and storage of samples.
Enzyme Half-Life
- Enzyme half-life determines how long an enzyme remains active after being released into the blood.
- Knowledge of an enzyme's half-life is helpful for assessing when tissue injury or increased enzyme production occurred and whether the process is ongoing.
Tissue Specificity
- Tissue specificity of enzymes helps determine the tissue of origin of leakage. This includes the presence or absence of the enzyme in the tissue, its concentration, and where it goes after leakage or secretion.
- Serum enzyme activity is not a reliable indicator of the severity or location of tissue injury.
Isoenzymes and Isoforms
- Isoenzymes are enzymes that catalyze the same reaction but have different structures.
- Isoenzymes may differ in catalytic sites, activity, immunogenicity, and electrophoretic mobility.
- Examples include alkaline phosphatase (ALP), with intestinal and tissue non-specific isoforms, and lactate dehydrogenase (LDH), with isoforms based on heart and muscle subunits.
- Isoform measurement can be accomplished through various methods (electrophoresis, immunoassays, cellulose acetate electrophoresis, isoelectric focusing).
Liver
- Hepatocyte injury is assessed using Alanine aminotransferase (ALT).
- ALT is found in the liver, muscle, kidneys, and erythrocytes.
- Increased serum ALT activity commonly signals hepatocellular injury.
- ALT is not a reliable indicator of liver disease in large animals.
- Increased serum activity peaks about 48 hours post-injury, then decreases. The serum half-life of ALT is roughly 2–3 days in dogs.
Aspartate Aminotransferase (AST)
- AST is a cytoplasmic and mitochondrial enzyme found in various tissues, including skeletal, cardiac, and liver muscle, and erythrocytes.
- Increased AST activity indicates liver or muscle injury.
- The activity usually begins to increase around 24-36 hours after injury, and decreases more slowly than serum CK.
Glutamate Dehydrogenase (GLDH)
- GLDH is a mitochondrial indicator of liver injury and is found in several other organs.
Alkaline Phosphatase (ALP)
- ALP is a non-specific enzyme that hydrolyzes phosphate esters.
- Liver and bone are the major sources of ALP.
- Increased serum ALP activity is a sensitive indicator of cholestasis (gallbladder or extrahepatic bile duct obstruction) in dogs but is less useful in other species.
Gamma-Glutamyl Transferase (GGT)
- GGT is a membrane-bound enzyme involved in hepatic and biliary function.
- GGT originates primarily from the liver and can indicate potential issues with the biliary system.
- Increased serum GGT activity is commonly associated with cholestasis, and biliary hyperplasia.
Pancreatic enzymes
- Amylase activity is used to test for pancreatitis.
- Pancreatic lipase activity plays a central role in fat digestion and is useful to identify potential pancreatic disorders.
- Elevated lipase activity is often associated with pancreatitis in dogs, cats, and ruminants compared to amylase.
- Testing for lipase is more sensitive for identification of pancreatitis in many species than testing for amylase, especially cats.
Creatine Kinase (CK)
- CK is an enzyme primarily found in skeletal and cardiac muscle.
- Increased serum CK activity often indicates muscle injury or inflammation, as it is rapidly elevated and returns to normal within 24–48 hours after an acute insult.
Serum Protein Electrophoresis (SPE)
- SPE analysis separates serum proteins into albumin, alpha-1, alpha-2, beta-1, beta-2, and gamma fractions.
- Albumin is the main serum protein, and the globulin fractions include diverse proteins, including immunoglobulins.
- Increased or decreased concentrations of protein fractions indicate potential problems or underlying diseases.
Acute Phase Proteins (APPs)
- APPs are proteins whose concentrations change significantly (>25%) in response to inflammation and are used as markers for inflammatory conditions.
- Increase in APPs occurs within 24–48 hours post-inflammation.
Plasma Ammonia
- Ammonia (ammonium) is produced in the gastrointestinal tract from microbial breakdown of proteins, and is converted in the liver to urea.
- Ammonia is removed by the urea cycle, and elevated levels can be associated with liver insufficiency, or other non-hepatic causes.
- Blood ammonia concentration is often elevated in animals with hepatic encephalopathy.
Clinical evaluation of plasma proteins
- Evaluation of A/G ratios and serum protein concentrations aids in diagnosing various diseases (i.e. acute phase response, overhydration, concurrent conditions).
- Dehydration, increased water intake, may result in elevated protein levels.
Tests of Carbohydrate Assimilation (Glucose Absorption Test)
- Glucose absorption tests are useful for assessing carbohydrate absorption in monogastric mammals, but not ruminants.
- Glucose is administered, and blood samples are collected at various time intervals.
- Adequate intestinal absorption is indicated if the glucose concentration doubles at 120 minutes compared to basal levels.
- This test is performed primarily in horses in cases of chronic weight loss.
Electrolytes - Basic Concepts
- Electrolytes include sodium (Na+), chloride (Cl-), potassium (K+), calcium (Ca2+), phosphate (PO4), and magnesium (Mg2+).
- Electrolyte concentrations are measured in whole blood, plasma, or serum and these are determined by four processes : intake, shifts between ICF and ECF, increased renal retention, and increased loss via the kidneys, alimentary tract, skin, or airways.
Liver Physiology and Diseases
- The liver is a vital organ with many metabolic and excretory functions.
- Liver disease encompasses various conditions affecting hepatocytes, bile ducts, or portal circulation.
- Liver dysfunction can cause abnormalities in serum enzymes, bile acids, and other substances.
Urinary System
- Glomerular filtration rate (GFR) is the primary measure of renal function and is estimated using serum urea, serum creatinine, and symmetric dimethylarginine (SDMA).
- Renal tubular function can also be tested through urine specific gravity (SG).
- Urea is a byproduct of protein catabolism which is produced in the liver. Serum levels increase during renal dysfunction
- Creatinine is predominantly produced by muscle metabolism, and serum levels increase in response to renal disease.
Urine Analysis
- Urine analysis involves physical (clarity, colour, odour) and chemical (e.g., pH, specific gravity, protein, glucose, ketones, blood) assessments.
- Microscopic examination of the urine sediment assesses for cells, casts, and crystals.
- These analyses are essential for diagnosing numerous urinary tract disorders, and assessing animal's health.
Clinical Enzymology
- Overview of enzymology topics in clinical pathology.
- Detailed mechanisms about leakage versus induced and enzyme half-life's, importance and implications of tissue-specificity and proper handling/storage.
- Specific serum enzyme assays and their clinical relevance (e.g. ALT, AST, GGT, GLDH, CK, lipase, amylase, bilirubin)
- Methods to assess and interpret results of these tests.
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Description
Test your knowledge on liver and muscle injury biomarkers, including serum GLDH, SDH, and CK activities. This quiz explores the specific enzymes involved and their clinical implications. Perfect for students in veterinary biochemistry or clinical pathology courses.
