Clinical Chemistry: Amylase Reference Range
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Questions and Answers

What is the typical onset time for amylase to rise in cases of acute pancreatitis?

  • 1-2 hours
  • 24 hours
  • 5-8 hours (correct)
  • 10-12 hours

    • At what point does amylase levels peak following the onset of acute pancreatitis?

  • 12 hours
  • 48 hours
  • 24 hours (correct)
  • 5 hours

    • How long does it typically take for amylase levels to normalize after an episode of acute pancreatitis?

  • 3-5 days (correct)
  • 7-10 days
  • 10-14 days
  • 1-2 days

    • How does the timing of lipase elevation compare to that of amylase in acute pancreatitis?

    <p>Lipase rises later than amylase</p> Signup and view all the answers

    What does the amylo-clastic method measure?

    <p>The disappearance of starch substrate</p> Signup and view all the answers

    What is the duration for which lipase levels remain elevated in acute pancreatitis?

    <p>7 days</p> Signup and view all the answers

    What is the classic reference method that measures reducing sugars?

    <p>Somogyi method</p> Signup and view all the answers

    What happens to the starch-iodine complex during the amylo-clastic method?

    <p>It decreases in color intensity</p> Signup and view all the answers

    Which component is essential for the saccharogenic method to function?

    <p>Starch substrate</p> Signup and view all the answers

    What is the relationship between reducing sugars and amylase activity in the saccharogenic method?

    <p>Reducing sugars are directly proportional to AMY activity</p> Signup and view all the answers

    What is the principle behind the chromogenic method of measuring amylase activity?

    <p>It involves the formation of a dye-substrate complex that changes color.</p> Signup and view all the answers

    In continuous-monitoring method for amylase activity, what type of change is measured?

    <p>Change in absorbance of NAD+ at 340 nm.</p> Signup and view all the answers

    What is the optimal pH for amylase activity?

    <p>6.9</p> Signup and view all the answers

    What is indicated by an increase in color intensity in the chromogenic method for amylase?

    <p>Increase in amylase activity.</p> Signup and view all the answers

    Which of the following statements about the chromogenic method is true?

    <p>The hydrolysis of the substrate produces water-soluble dye fragments.</p> Signup and view all the answers

    What is the primary specimen type recommended for amylase testing?

    <p>Serum or heparinized plasma</p> Signup and view all the answers

    What is the reference range for serum amylase in U/L?

    <p>28 to 100 U/L</p> Signup and view all the answers

    Which factor is known to significantly affect most amylase measurement methods?

    <p>Hemolysis</p> Signup and view all the answers

    What is the enzyme classification for lipase?

    <p>EC 3.1.1.3</p> Signup and view all the answers

    Which of the following statements about lipase is correct?

    <p>Lipase targets fatty acid residues at positions 1 and 3 of triglycerides</p> Signup and view all the answers

    Which substances act as accelerators for lipase activity?

    <p>Colipase and bile salts</p> Signup and view all the answers

    What is the maximum recommended level of amylase in urine, as defined in the reference range?

    <p>15 U/h</p> Signup and view all the answers

    Which of the following is NOT a function of lipase?

    <p>Reforming triglycerides</p> Signup and view all the answers

    What is the optimal pH for amylase (AMY) activity?

    <p>6.9</p> Signup and view all the answers

    Which of the following conditions is NOT a source of error affecting amylase (AMS) measurement?

    <p>High carbohydrate meal</p> Signup and view all the answers

    How long can amylase (AMY) remain stable at room temperature?

    <p>1 week</p> Signup and view all the answers

    Which medication is associated with falsely increasing amylase (AMS) levels?

    <p>Morphine</p> Signup and view all the answers

    What method is used to continuously monitor amylase activity?

    <p>Coupling of multiple enzyme systems</p> Signup and view all the answers

    At what temperature can amylase (AMY) be stored for up to 2 months without significant loss of activity?

    <p>4°C</p> Signup and view all the answers

    Which of the following substances can falsely decrease amylase (AMS) levels?

    <p>Wheat germ lectin</p> Signup and view all the answers

    What is measured at 340 nm in the continuous-monitoring method for amylase activity?

    <p>Absorbance of NAD+</p> Signup and view all the answers

    Study Notes

    Amylase (AMS) Overview

    • Specimen types: serum or heparinized plasma; avoid saliva contamination, which has 700 times higher amylase content than serum.
    • Hemolysis generally does not affect most testing methods, except for coupled-enzyme methods involving peroxidase reactions.
    • Reference range for serum: 28 to 100 U/L (37°C) or 0.5 to 1.7 µkat/L; urine reference range: 1 to 15 U/h.

    Lipase (LPS) Function

    • Enzyme classification: EC 3.1.1.3, known as triacylglycerol acylhydrolase.
    • Hydrolyzes ester linkages in fats, producing alcohols and fatty acids.
    • Primarily targets fatty acid residues at positions 1 and 3 of triglycerides.
    • Colipase and bile salts act as accelerators for lipase activity.

    Diagnostic Significance of Amylase in Acute Pancreatitis

    • Amylase levels rise within 5-8 hours of onset, peak at 24 hours, and normalize after 3-5 days.
    • Lipase levels rise within 4-8 hours, peak at 24 hours, and normalize after 7-14 days.

    Assay Methods for Enzyme Activity of Amylase

    • Amyloclastic Method: Measures disappearance of starch substrate, where hydrolysis releases iodine resulting in a decrease in dark-blue color intensity proportional to amylase concentration.
    • Saccharogenic Method: Measures appearance of reducing sugars from starch hydrolysis, with results reported in Somogyi units.
    • Chromogenic Method: Involves starch substrate linked to a chromogenic dye; hydrolysis yields soluble dye fragments, with increased color intensity proportional to amylase activity.
    • Continuous-Monitoring Method: Monitors changes in absorbance of NAD+ at 340 nm to assess amylase activity, with optimal pH at 6.9.

    Sources of Errors in Amylase Measurement

    • Stability: Amylase remains stable at room temperature for 1 week and at 4°C for 2 months.
    • Inhibitors that falsely lower amylase levels include increased plasma triglycerides, wheat germ lectin, and chelating agents like EDTA, citrate, and oxalate.
    • Certain medications, particularly morphine and opiates, can cause falsely elevated amylase levels by inducing constriction in the sphincter of Oddi and pancreatic ducts, leading to the regurgitation of amylase into serum due to increased pressure.

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    Description

    This quiz covers the handling of specimens for amylase testing and its reference ranges in clinical chemistry. Understand the importance of avoiding saliva contamination and the effects of hemolysis on amylase levels. Test your knowledge on the correct procedures and reference values for serum and urine amylase.

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