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110 Cards in this Set
- Front
- Back
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What two types of enzyme can appear in the serum? |
Serum enzymes and Cellular Enzymes |
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Give four reasons why cellular enzyme levels would be increased in the serum. |
1) spillage from physical trauma |
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True or false: Measuring the level of one enzyme will generally allow you to identify the cause and source of disease. |
False; You will always try to get as complete of a picture of patient health as possible, so looking at just one enzyme is almost never enough. |
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List 3 ways to improve the significance of the value of enzyme measurement. |
1) Correlate with clinical findings and history |
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True or false: looking at one enzyme can be significant in assessing the severity of disease and monitoring treatment response. |
True: Even just one enzyme can help give you clues to the whole picture! You can't make a diagnosis from one, but you can monitor patient health by looking at them. |
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What are the two basic types of enzyme assay? |
1) Substrate depletion |
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True or false: In an enzymatic pathway, the amount of enzyme is in excess and the amount of reagent determines the rate of the reaction. |
False: The enzyme determines the rate of reaction, and the reagents are in excess. |
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Two site assays increase the ________ of a reaction, while a probe for signal enhancement would increase the _________ of the assay. |
Specificity, Sensitivity |
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Name two types of probes for enhancing enzyme assay sensitivity. |
1) Enzymes that catalyze fluorogenic reactions |
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What type of test do we use to look for tissue specific isoenzymes? |
Immunoassay |
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Lactate dehydrogenase converts ________ to __________. |
Lactate, pyruvate |
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What enzyme is key in carbohydrate metabolism? |
Lactate dehydrogenase |
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How many isoenzymes does lactate dehydrogenase have? |
5 |
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True or false: Lactate dehydrogenase is widely distributed throughout the body, so elevations are not diagnostic. |
True |
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Which isoenzyme of lactate dehydrogenase is most sensitive to the cold? |
LD5; it has many LD-M subunits, which are sensitive to the cold |
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At what temperature should you store lactate dehydrogenase samples? |
Room temperature until analysis |
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True or false: lactate dehydrogenase can use either lactate OR pyruvate as its substrate. |
True |
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What common cell type found in the body can severely skew a lactate dehydrogenase activity assay? |
Red Blood Cells; have 500X more LDH activity |
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In a myocardial infarction, you should see a flip in the __/__ ratio of lactate dehydrogenase. |
LD1/LD2 |
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What type of bonds can amylase break? |
alpha-1-4 bonds |
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What are the two classes of amylase? |
1) S type: Salivary amylase |
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True or false: Serum usually contains more salivary amylase than pancreatic amylase. |
True |
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What are the four types of amylase assays? |
1) Iodometric: Measures disappearance of purple colored starch-iodine complex |
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What is the pH required for amylase assays? |
pH 6.9-7.0 |
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Which common conditions increase amylase concentration? |
Pancreatitis, salivary gland insult, ovarian disorder, amylase producing tumor, drugs |
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What disease is an amylase test diagnostic for? |
Pancreatitis (90% specificity) |
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True or false: Amylase is the only enzyme that appears in a healthy person's urine. |
True |
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What is the reference range for amylase? |
<115 U/L |
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What inhibits amylases? |
Lipemic serum, oxalate, citrate, EDTA |
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True or false: Amylase is unstable in serum. |
False: it is stable in the serum. |
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True or false: Cholinesterase is a type of transaminase. |
False: Cholinesterase is a hydrolase.
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What are the two isoenzymes of cholinesterase? |
1) Psuedocholinesterase: Hepatic synthesis |
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Acetylcholine binding to its receptor triggers a __________ channel to open. |
Sodium |
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What can interfere with a cholinesterase assay? |
Hemolysis; cholinesterase is produced in RBCs |
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What are the required samples for a cholinesterase assay? |
Heparin or EDTA plasma sample |
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True or false: Males typically have more cholinesterase than females. |
True |
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What three conditions can cause increased acetylcholinesterase? |
1) Hemolytic diseases |
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What two conditions can cause decreased acetylcholinesterase? |
1) Organophosphate/carbamate poisoning |
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People who suffer from Suxamethonium Sensitivity have a genetic deficiency of what specific enzyme?
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Cholinesterases |
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The test for acetylcholine looks for the 25 common ____________ of the enzyme, all of which produce characteristic patterns of sensitivities to different inhibitors. |
polymorphisms |
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In what tissues is Gamma Glutamyl Transferase (GGT) found? |
Renal tubules, bile canaliculi, heart, pancreas, lungs, seminal vesicles |
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True or false: All GGT molecules have the same molecular size. |
False, due to post transcriptional modification |
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What common "drug" will increase GGT? |
Alcohol |
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What enzyme is the first and most sensitive indicator of any type of liver dysfunction (but has little diagnostic value)? |
GGT |
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What type of assay does the GGT test utilize? |
Colorimetric assay |
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What are the reference ranges of GGT for males and females? |
Male: 6-45 U/L |
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Acid phosphotases typically ____________ enzymes. |
De-phosphorylate/Deactivate |
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Where is acid phosphotase typically found in the tissues? |
Prostate in males |
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True or false: Acid phosphotase is specific for one substrate. |
False: |
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The acid phosphotase assay allows you to measure all of the specific ___________. |
Isoenzymes |
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What type of assay is the Acid phosphotase assay? |
Immunometric assay |
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What are the most common causes of acid phosphotase elevation? |
Platelet destruction, myelocytic leukemia, increased osteoclast (bone breakdown cell) activity |
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What are large macrophages in the bone marrow called? |
Gaucher Cells |
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What is the reference range for acid phosphotase? |
Males: 2-12 U/L |
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What will interfere with acid phosphotases? |
Hemolysis, lipemia, rectal digital exams |
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What three things should you do to an acid phosphotase sample? Why? |
1) Draw in an EDTA tube |
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What is the primary organ that produces lipase? |
Pancreas |
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Lipases hydrolyze the ester linkages of triglycerides to _______ and _______ at an ester-water interface. |
Free fatty acids; alcohols |
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What type of assay is used to measure the fatty acids released by lipase? |
Turbidometry assay |
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What are the two different things that can be measured in lipase tests? |
Released fatty acids and glycerol |
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What diseases can cause elevated lipase? |
Pancreatitis/duct abstruction |
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True or false: Lipase tests can be diagnostic for acute pancreatitis? |
False; they are confirmatory tests for clinical suspicion of pancreatitis |
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True or false: An elevated lipase test result directly correlates with disease severity. |
False; rise does not correlate with severity |
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In proximal renal tubular disease, lipase will appear in the _______. |
Urine |
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What is the reference range for lipase? |
10-60 U/L |
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What causes interference with lipase? |
Hemoglobin inhibits lipase activity. |
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True or false: Lipase is highly stable in the serum. |
True |
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The function of Alanine aminotransferase is to convert __________ into ____________ and pyruvate. |
Alanine to glutamate |
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True or false: The alanine aminotransferase test directly measures enzyme activity. |
False; the NAD generated from the pyruvate being converted to lactate by LDH is measured. |
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Where is alanine aminotransferase found in the highest concentration? |
The liver (3000x more than in serum) |
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Alanine aminotransferase is specific for what type of disease? |
Hepatocellular disease, not including obstructive biliary damage |
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What test is generally ordered with an alanine aminotransferase test? |
Aspartate aminotransferase (AST) |
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True or false: The amount of elevation seen in an alanine aminotransferase assay is directly correlated with the extend of patient damage. |
True; this is a good way to measure recovery from a liver insult |
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What is the reference range for alanine aminotransferase? |
6-37 U/L |
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Alanine aminotransferase has a half life of approximately _______ hours. |
48 |
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What can interfere with alanine aminotransferase? |
RBCs |
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What is the preferred sample for alanine aminotransferase? |
Serum sample |
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Where is aspartate aminotransferase found that alanine aminotransferase isn't? |
Heart and skeletal muscle |
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A low ALT and a high AST rules out what? |
Liver damage as a cause of high AST; look for heart/muscle damage |
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What is measured in an aspartate aminotransferase (AST) assay? |
NAD+ concentration |
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What are the two isoenzymes of AST? |
Cytoplasmic and mitochondrial |
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What causes mitochondrial AST release? |
Necrotic tissue damage |
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True or false: Isoenzymes of AST are commonly looked at separately in the AST assay. |
False |
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What conditions cause increased AST levels? |
Myocardial infarction |
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Alkaline phosphotases are a group of _____________ enzymes that act on phosphate esters at alkaline pH. |
Hydrolytic |
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Where are alkaline phosphotases found? |
GI tract, liver, bone, spleen, placenta, kidney |
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What are the four isoenzymes of alkaline phosphotase? |
1) Liver/Bone/Kindey |
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How do you differentiate between the isoenzymes of alkaline phosphotase in the lab? |
Electrophoresis |
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In which conditions do you see a high alkaline phosphotase (ALP) level? |
Hepatobiliary disorders |
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In which conditions do you see a low alkaline phosphotase level? |
Inherited absence of alk phos |
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In which disease do you see the highest alkaline phosphotase level? |
Paget's Disease= bone cirrhosis |
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True or false: ALP will be high in hepatocellular disorders. |
False; hepatobiliary disorders |
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True or false: An elevated alkaline phosphotase level is always diagnostically useful. |
False |
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What is the reference range for alkaline phosphotase? |
1-12 yo: 350 U/L (due to growing) |
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What can interfere with Alkaline phosphotase levels? |
Hemolysis |
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True or false: alkaline phosphotase is thermolabile. |
True |
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Where is creatine kinase found in the cell? |
Cytoplasm |
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What type of enzyme is creatine kinase? |
Phosphotransferase |
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What are the isoenzymes of creatine kinase? |
MM (Muscle), MB (heart) , and BB (Brain) |
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What causes creatine kinase to be irreversibly deactivated? |
Light; it is an unstable enzyme due to this |
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What type of assay is used to measure creatine kinase levels? |
Immunoassay (no interference via hemolysis/light) |
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What will cause creatine kinase to be 10X the upper level of normal? |
Polymyositis |
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What will cause creatine kinase to be 5-9X the upper level of normal? |
Surgery |
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What will cause creatine kinase to be 1-4X the upper level of normal? |
Physiological differences |
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What is the formula for the Creatine Kinase Index? |
CKMB MASS |
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A ____________ is a complex of serum proteins and antibodies that can be very high in molecular weight (which can keep the kidneys from clearing them causing interference with tests. |
Macro-analyte |
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What are the two most common Macro-analytes? |
Macro-Prolactin |
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What is the easiest method for getting rid of macro-complexes? |
Using polyethylene glycol precipitation (acts like a sponge to macro complexes) |
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What is macroamylase made of? |
Amylase bound to IgA |
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What is the De Ritis Ratio: |
AST |
