Clinical Enzymes Quiz
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Questions and Answers

What is the major tissue source of Aspartate Aminotransferase (AST)?

  • Cardiac tissue (correct)
  • Kidney
  • Pancreas
  • Liver
  • Which condition is associated with an increased level of Tartrate-resistant acid phosphatase (TRAP)?

  • Hairy cell leukemia (correct)
  • Chronic alcoholism
  • Gaucher's disease
  • Acute Myocardial Infarction
  • Which enzyme is more liver-specific compared to Aspartate Aminotransferase (AST)?

  • Alkaline Phosphatase
  • Lactate Dehydrogenase (LDH)
  • Alanine Aminotransferase (ALT) (correct)
  • Gamma-Glutamyl Transferase (GGT)
  • What diagnostic significance does an increase in Alanine Aminotransferase (ALT) indicate?

    <p>Hepatic disorders (D)</p> Signup and view all the answers

    When do Aspartate Aminotransferase (AST) levels peak after an acute myocardial infarction (AMI)?

    <p>24 hours (B)</p> Signup and view all the answers

    What is a common method used to measure Aspartate Aminotransferase (AST) concentration?

    <p>Karmen Method (D)</p> Signup and view all the answers

    Which condition correlates with increased levels of transferases?

    <p>Viral hepatitis (C)</p> Signup and view all the answers

    Which factor can inhibit the activity of Aspartate Aminotransferase (AST)?

    <p>Heparin (C)</p> Signup and view all the answers

    What is the De Ritis ratio (ALT:AST) in acute hepatitis?

    <blockquote> <p>1.0 (C)</p> </blockquote> Signup and view all the answers

    Which condition would most likely cause a severe elevation of transferase levels?

    <p>Severe viral hepatitis (C)</p> Signup and view all the answers

    What is the main function of amylase (AMS)?

    <p>Break down starch and glycogen (A)</p> Signup and view all the answers

    Which method of measuring amylase activity employs the hydrolysis of starch?

    <p>Saccharogenic method (B)</p> Signup and view all the answers

    What condition is most commonly linked to increased serum amylase levels?

    <p>Acute pancreatitis (B)</p> Signup and view all the answers

    What is the end product of lipase activity during the Cherry Crandal method?

    <p>Fatty acids (A)</p> Signup and view all the answers

    Which enzyme is characterized by having two possible forms, H and M?

    <p>Lactate dehydrogenase (C)</p> Signup and view all the answers

    What is the major tissue source of lipase?

    <p>Pancreas (D)</p> Signup and view all the answers

    What condition is associated with the highest elevations of bone alkaline phosphatase (ALP)?

    <p>Osteitis deformans (C)</p> Signup and view all the answers

    Which blood groups increase intestinal alkaline phosphatase (ALP) after a fatty meal?

    <p>O or B (A)</p> Signup and view all the answers

    Which alkaline phosphatase (ALP) variant is inhibited by L-leucine?

    <p>Nagao ALP (B)</p> Signup and view all the answers

    In what order is alkaline phosphatase (ALP) heat stability ranked from highest to lowest?

    <p>Placental, Bone, Intestinal, Liver (C)</p> Signup and view all the answers

    What method is considered the most specific for measuring alkaline phosphatase?

    <p>Bowers and Mc Comb method (B)</p> Signup and view all the answers

    Which condition is not commonly associated with increased alkaline phosphatase levels?

    <p>Zinc deficiency (C)</p> Signup and view all the answers

    How is acid phosphatase (ACP) activity indicative of seminal fluid presence in a sample?

    <p>ACP activity &gt;50 IU/L (B)</p> Signup and view all the answers

    Which method improves the separation of bone and liver alkaline phosphatases (ALP)?

    <p>Neuraminidase and wheat germ lectin (C)</p> Signup and view all the answers

    What is the expected time frame for LD levels to begin rising after an acute myocardial infarction (AMI)?

    <p>Within 12-24 hours (A)</p> Signup and view all the answers

    Which condition is associated with a markedly increased LD-5 level?

    <p>Hepatic carcinoma (B)</p> Signup and view all the answers

    What characteristic does LD-1> LD-2 indicate?

    <p>Flipped pattern seen in myocardial infarction (B)</p> Signup and view all the answers

    Which method for measuring LD levels is performed at pH 8.8?

    <p>Wacker Method (B)</p> Signup and view all the answers

    What happens to LD values if samples are frozen?

    <p>LD values decrease since LD-S is cold-labile (B)</p> Signup and view all the answers

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    Flashcards

    Alkaline Phosphatase (ALP)

    An enzyme that is active at a basic pH and is often elevated in bone disease.

    Bone ALP Isoenzyme

    ALP isoenzyme found in bone, increases due to osteoblastic activity, especially during growth and in older adults.

    Intestinal ALP Isoenzyme

    ALP isoenzyme found in the intestines, its presence in serum depends on blood group, often elevated after fatty meals.

    Carcinoplacental ALP

    An ALP isoenzyme found in various cancers. Regan ALP is the most heat stable, found in lung, breast, ovarian and gynecological cancers. Nagao ALP is a variant found in pancreatic and bile duct adenocarcinoma.

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    Electrophoresis

    A method to separate and identify different ALP isoenzymes based on their migration in an electric field.

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    Heat Fractionation/Stability Test

    A test that uses different temperatures to distinguish ALP isoenzymes based on their heat stability. Placental ALP is the most stable, while bone ALP is the least.

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    Chemical Inhibition Test

    A method to inhibit ALP isoenzymes using specific chemicals like phenylalanine, urea, and levamisole. Each reagent inhibits different isoenzymes.

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    Acid Phosphatase (ACP)

    An enzyme active at acidic pH, often elevated in the presence of seminal fluid in a sample.

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    Thymolphthalein Monophosphate

    A specific substrate for measuring ACP activity.

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    Tartrate-Resistant Acid Phosphatase (TRAP)

    A form of ACP resistant to tartrate inhibition, found elevated in certain leukemias and lymphomas.

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    Aspartate Aminotransferase (AST)

    An enzyme found in high concentrations in the liver, heart, and skeletal muscle.

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    Alanine Aminotransferase (ALT)

    An enzyme found in high concentrations in the liver, more liver-specific than AST.

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    Enzymatic Assay

    The process of measuring enzyme activity.

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    Pyridoxal Phosphate (Vitamin B6)

    An essential coenzyme required by many enzymes, including AST and ALT.

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    Acute Hepatitis

    A significant increase in the levels of the AST and ALT enzymes is often observed in this condition.

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    What is ALT (Alanine aminotransferase)?

    A liver enzyme that catalyzes the transfer of an amino group from an amino acid to an alpha-keto acid.

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    What is AST (Aspartate aminotransferase)?

    A liver enzyme that catalyzes the transfer of an amino group from aspartate to alpha-ketoglutarate.

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    What is the De Ritis Ratio?

    Ratio of ALT to AST, often used in diagnosing liver diseases. Values over 1.0 suggest acute hepatitis.

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    What is Amylase?

    An enzyme that breaks down starch and glycogen, crucial for digesting carbohydrates.

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    What is S-type Amylase?

    A type of amylase found in saliva, also known as ptyalin.

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    What is P-type Amylase?

    A type of amylase found in the pancreas, also known as amylopsin.

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    What is Lipase?

    A pancreatic enzyme that breaks down fats (triacylglycerols) into fatty acids and glycerol.

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    What is Lactate Dehydrogenase (LD)?

    A hydrogen-transfer enzyme crucial in many metabolic processes, often elevated in hemolytic disorders and pernicious anemia.

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    What is "flipped pattern" in LD?

    LD-1 (H subunit) is elevated primarily in myocardial infarction (heart attack) and hemolytic anemia. This pattern is called "flipped" because LD-1 is higher than LD-2 in these conditions.

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    How does LD change after tissue damage?

    LD levels rise within 12-24 hours after damage, peak within 48-72 hours, and remain elevated for 10-14 days. Different conditions lead to different LD patterns.

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    How does LD-5 behave in liver diseases?

    Liver diseases, like viral hepatitis and cirrhosis, cause a moderate increase in LD-5. However, in hepatic carcinoma (liver cancer) and toxic hepatitis, LD-5 is significantly elevated.

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    What's special about LD-6?

    LD-6 is associated with the alcohol dehydrogenase enzyme, which breaks down alcohol. Elevated levels of LD-6 indicate drug hepatoxicity (liver damage from drugs), obstructive jaundice, and methanol poisoning.

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    Study Notes

    Alkaline Phosphate/Alkaline Orthophosphoric Monoester Phosphohydrolase

    • Bone isoenzyme increases with osteoblastic activity, elevated in children and adults over 50.
    • Intestinal ALP presence depends on blood type (secretor gene and H substance). B or O blood group increases after a fatty meal.
    • Elevated in bone disorders like Paget's disease (osteitis deformans) and dialysis patients.
    • Carcinoplacental ALP is found in cancers (lung, breast, ovarian, gynecological) and is heat-stable.
    • Nagao ALP is a variant, inhibited by L-leucine and phenylalanine, found in certain cancers.

    Methods for ALP Analysis

    • Heat Fractionation/Stability Test: Placental is heat-stable, bone is heat-labile.
    • Chemical Inhibition Test: Phenylalanine inhibits placental and intestinal ALP, urea inhibits bone ALP, and levamisole inhibits liver and bone ALP.
    • Bowers and McComb (Szasz modification) is considered the most specific method.

    Decreased ALP

    • Zinc deficiency

    Increased ALP

    • Osteitis deformans
    • Obstructive jaundice

    Acid Phosphatase/ Acid Orthophosphoric Monoester Phosphohydrolase

    • Catalyzes the same reaction as ALP but is active at pH 5.0.
    • ACP activity >50 IU/L indicates seminal fluid in the sample.
    • Used for detecting prostatic adenocarcinoma.
    • Helpful in forensic cases (rape investigations).
    • Thymolphthalein monophosphate is a specific substrate.
    • Must be free from hemolysis.

    Increased ACP (with Metastatic Bone Involvement)

    • Prostatic carcinoma
    • Breast, lung, and thyroid carcinoma
    • Gaucher's disease
    • Niemann Pick Disease

    Aspartate Aminotransferase (AST)

    • Two isoenzyme fractions (cytoplasm and mitochondrial AST).
    • Cytoplasmic isoenzyme is predominant in serum.
    • Found in cardiac tissue, liver, and skeletal muscle.
    • Useful in evaluating myocardial infarction, hepatocellular disorders, and skeletal muscle involvement.

    Alanine Aminotransferase (ALT)

    • Similar enzymatic activity to AST
    • High concentration in the liver.
    • More liver-specific than AST.
    • Very significant in evaluating hepatic disorders.
    • More sensitive and specific for post-transfusion hepatitis and occupational toxic exposures than AST.
    • Requires pyridoxal phosphate (vitamin B6) as a coenzyme.
    • Hemolysis should be avoided; heparin may inhibit some AST methods.

    Increased Transferases

    • Toxic hepatitis
    • Acute myocardial infarction
    • Wolff-Parkinson White Syndrome
    • Trichinosis
    • Chronic alcoholism
    • Dermatomyositis
    • Reye's syndrome
    • Viral hepatitis
    • Muscular dystrophy
    • Acute pancreatitis

    Amylase/Alpha-1-4 Glucan-4-glucohydrolase (AMS)

    • Catalyzes starch and glycogen breakdown, important in starch digestion.
    • Smallest enzyme (50,000-55,000 daltons)
    • Earliest pancreatic marker
    • Isoenzymes: S-type (ptyalin) and P-type (amylopsin) found in normal serum.

    Methods for Amylase analysis

    • Saccharogenic: Classic method, measures reducing sugars produced by starch hydrolysis.
    • Amyloclastic: Measures amylase activity by following substrate concentration decrease.
    • Chromogenic: Measures amylase activity via color change from substrate dye reaction.
    • Coupled-enzyme: Measures amylase activity via continuous monitoring.

    Increased Serum Amylase

    • Acute pancreatitis
    • Ectopic pregnancy
    • Peptic ulcers
    • Alcoholism
    • Mumps-parotitis

    Lipase (LPS)/Triacylglycerol Acylhydrolase

    • Plasma concentrations typically normal in salivary gland involvement.
    • Major tissue source is the pancreas.

    Lactate Dehydrogenase (LD)

    • Hydrogen-transfer enzyme using NAD+.
    • Tetrameric molecule with H and M subunits.
    • Highest serum levels seen in pernicious anemia and hemolytic disorders.
    • Elevated in AMI within 12-24 hours, peaking at 48-72 hours, elevated for 10-14 days.
    • Hepatic carcinoma and toxic hepatitis show significantly elevated values.
    • Elevated in viral hepatitis and cirrhosis.
    • LD-5 is increased in acute viral hepatitis, cirrhosis, and hepatic carcinoma.
    • LD-1 > LD-2 ("flipped pattern") in myocardial infarction and hemolytic anemia.

    Creatine Kinase (CK)

    • Dimeric molecule with M and B monomers.
    • Primarily found in muscles and brain (CK-BB is predominant brain isoenzyme).
    • CK-MB is significantly elevated in myocardial tissues.

    5'-Nucleotidase (5'N)

    • Phosphoric monoester hydrolase, primarily secreted from the liver.
    • Marker for hepatobiliary disease and liver infiltrative lesions.

    Gamma-glutamyl transferase (GGT)

    • Useful in differentiating the cause of an increased ALP level.
    • Elevated in hepatobiliary disorders and biliary tract obstructions,.

    Pseudocholinesterase (PChE)

    • Liver-secreted enzyme reflecting synthetic function rather than hepatocyte injury.
    • Removes the benzyl group from cocaine.
    • Marker for insecticide/pesticide poisoning (organophosphate poisoning); low PChE levels are seen.
    • Useful to monitor the impact of muscle relaxants (such as succinylcholine) after surgery.

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    Description

    Test your knowledge on clinical enzymes and their significance in medical diagnostics. This quiz covers various enzymes including Aspartate Aminotransferase (AST), Alanine Aminotransferase (ALT), and amylase. Explore the relationships between enzyme levels and specific medical conditions.

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