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Questions and Answers
What is the major tissue source of Aspartate Aminotransferase (AST)?
What is the major tissue source of Aspartate Aminotransferase (AST)?
Which condition is associated with an increased level of Tartrate-resistant acid phosphatase (TRAP)?
Which condition is associated with an increased level of Tartrate-resistant acid phosphatase (TRAP)?
Which enzyme is more liver-specific compared to Aspartate Aminotransferase (AST)?
Which enzyme is more liver-specific compared to Aspartate Aminotransferase (AST)?
What diagnostic significance does an increase in Alanine Aminotransferase (ALT) indicate?
What diagnostic significance does an increase in Alanine Aminotransferase (ALT) indicate?
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When do Aspartate Aminotransferase (AST) levels peak after an acute myocardial infarction (AMI)?
When do Aspartate Aminotransferase (AST) levels peak after an acute myocardial infarction (AMI)?
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What is a common method used to measure Aspartate Aminotransferase (AST) concentration?
What is a common method used to measure Aspartate Aminotransferase (AST) concentration?
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Which condition correlates with increased levels of transferases?
Which condition correlates with increased levels of transferases?
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Which factor can inhibit the activity of Aspartate Aminotransferase (AST)?
Which factor can inhibit the activity of Aspartate Aminotransferase (AST)?
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What is the De Ritis ratio (ALT:AST) in acute hepatitis?
What is the De Ritis ratio (ALT:AST) in acute hepatitis?
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Which condition would most likely cause a severe elevation of transferase levels?
Which condition would most likely cause a severe elevation of transferase levels?
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What is the main function of amylase (AMS)?
What is the main function of amylase (AMS)?
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Which method of measuring amylase activity employs the hydrolysis of starch?
Which method of measuring amylase activity employs the hydrolysis of starch?
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What condition is most commonly linked to increased serum amylase levels?
What condition is most commonly linked to increased serum amylase levels?
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What is the end product of lipase activity during the Cherry Crandal method?
What is the end product of lipase activity during the Cherry Crandal method?
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Which enzyme is characterized by having two possible forms, H and M?
Which enzyme is characterized by having two possible forms, H and M?
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What is the major tissue source of lipase?
What is the major tissue source of lipase?
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What condition is associated with the highest elevations of bone alkaline phosphatase (ALP)?
What condition is associated with the highest elevations of bone alkaline phosphatase (ALP)?
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Which blood groups increase intestinal alkaline phosphatase (ALP) after a fatty meal?
Which blood groups increase intestinal alkaline phosphatase (ALP) after a fatty meal?
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Which alkaline phosphatase (ALP) variant is inhibited by L-leucine?
Which alkaline phosphatase (ALP) variant is inhibited by L-leucine?
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In what order is alkaline phosphatase (ALP) heat stability ranked from highest to lowest?
In what order is alkaline phosphatase (ALP) heat stability ranked from highest to lowest?
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What method is considered the most specific for measuring alkaline phosphatase?
What method is considered the most specific for measuring alkaline phosphatase?
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Which condition is not commonly associated with increased alkaline phosphatase levels?
Which condition is not commonly associated with increased alkaline phosphatase levels?
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How is acid phosphatase (ACP) activity indicative of seminal fluid presence in a sample?
How is acid phosphatase (ACP) activity indicative of seminal fluid presence in a sample?
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Which method improves the separation of bone and liver alkaline phosphatases (ALP)?
Which method improves the separation of bone and liver alkaline phosphatases (ALP)?
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What is the expected time frame for LD levels to begin rising after an acute myocardial infarction (AMI)?
What is the expected time frame for LD levels to begin rising after an acute myocardial infarction (AMI)?
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Which condition is associated with a markedly increased LD-5 level?
Which condition is associated with a markedly increased LD-5 level?
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What characteristic does LD-1> LD-2 indicate?
What characteristic does LD-1> LD-2 indicate?
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Which method for measuring LD levels is performed at pH 8.8?
Which method for measuring LD levels is performed at pH 8.8?
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What happens to LD values if samples are frozen?
What happens to LD values if samples are frozen?
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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.
