Clinical Biochemistry: Calcium, Parathyroid Hormone, Vitamin D Quiz
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Questions and Answers

What is the main effect of vitamin D2 (ergocalciferol) on the body?

  • Increases secretion of parathyroid hormone
  • Increases absorption of calcium in the intestine (correct)
  • Decreases renal excretion of calcium
  • Decreases reabsorption of calcium in the kidneys

    • Which of the following can interfere with the analytic method for phosphate determination?

  • Oxalate, citrate or EDTA (correct)
  • Lithium heparin plasma
  • 24-hour urine
  • Serum

    • Which of the following is a potential cause of an elevated anion gap?

  • Hypoalbuminemia
  • Severe hypercalcemia
  • Methanol, ethanol, or ethylene glycol poisoning (correct)
  • Hyponatremia

    • What is the primary purpose of calculating the anion gap?

    <p>To determine the difference between measured and unmeasured anions</p> Signup and view all the answers

    What is the primary effect of excessive secretion or administration of growth hormone?

    <p>Increases reabsorption of calcium in the kidneys</p> Signup and view all the answers

    Which of the following is the most accurate method for determining phosphate levels?

    <p>Fiske-Subbarow method with ammonium phosphomolybdate complex (340 nm)</p> Signup and view all the answers

    Which of the following is the most important function of the Na*-K*-ATPase pumps?

    <p>To regulate the osmotic activity of plasma</p> Signup and view all the answers

    What is the primary cause of hyponatremia?

    <p>Increased movement of water into the cells, causing a decrease in serum/plasma sodium levels</p> Signup and view all the answers

    What is the primary cause of hyperchloremia?

    <p>Metabolic alkalosis with a tendency for the plasma chloride level to rise as the bicarbonate level increases</p> Signup and view all the answers

    Which method is considered the most accurate for the determination of chloride levels?

    <p>Ion-Selective Electrode</p> Signup and view all the answers

    What is the primary function of bicarbonate in the extracellular fluid (ECF)?

    <p>To serve as the major component of the buffering system in the blood</p> Signup and view all the answers

    Which of the following is the most accurate method for the determination of total carbon dioxide (CO2) in plasma?

    <p>Ion-Selective Electrode</p> Signup and view all the answers

    What is the primary function of magnesium in the body?

    <p>To act as an essential cofactor for more than 300 enzymes</p> Signup and view all the answers

    Which hormone is primarily responsible for the regulation of magnesium levels in the body?

    <p>Parathyroid hormone</p> Signup and view all the answers

    What is the recommended specimen for the determination of magnesium levels?

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

    Which of the following is the primary cause of an increased anion gap?

    <p>Metabolic acidosis caused by increased production or diminished excretion of organic acids</p> Signup and view all the answers

    Which hormone is responsible for regulating blood calcium levels?

    <p>Parathyroid hormone</p> Signup and view all the answers

    What is the typical range for normal plasma osmolality?

    <p>275-295 mOsm/kg</p> Signup and view all the answers

    Which element is not involved in the blood coagulation process?

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

    What is used to calculate the Osmolal Gap?

    <p>$2Na + 1.86 Na + glucose (mg/dl)$</p> Signup and view all the answers

    Which cation is the most abundant in the extracellular fluid?

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

    Which hormone stimulates the sensation of thirst in response to increased blood osmolality?

    <p>Arginine vasopressin</p> Signup and view all the answers

    What enzymatic activity does Aspartate Aminotransferase (AST) have?

    <p>Transfer of an amino group from alanine to a-ketoglutarate</p> Signup and view all the answers

    Which tissue has the highest concentration of Alanine Aminotransferase (ALT)?

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

    What is the diagnostic significance of Aspartate Aminotransferase (AST) in hepatic disorders?

    <p>Increased concentration in acute inflammatory conditions</p> Signup and view all the answers

    Which enzymatic activity does Alanine Aminotransferase (ALT) share with Aspartate Aminotransferase (AST)?

    <p>Transfer of an amino group from alanine to a-ketoglutarate</p> Signup and view all the answers

    What makes Alanine Aminotransferase (ALT) a more sensitive and specific screening test for posttransfusion hepatitis?

    <p>More liver-specific than Aspartate Aminotransferase (AST)</p> Signup and view all the answers

    Which of the following is the primary organ affected by elevated levels of Aspartate Aminotransferase (AST)?

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

    What is the primary role of the coupled enzymatic reaction in the measurement of Alanine Aminotransferase (ALT) activity?

    <p>To convert alanine and α-ketoglutarate into pyruvate and glutamate</p> Signup and view all the answers

    What is the primary function of the 2,4-DNPH reagent in the Reitman and Frankel method for measuring AST and ALT activities?

    <p>To act as a color developer for the spectrophotometric analysis</p> Signup and view all the answers

    Which of the following is the EARLIEST marker for the diagnosis of acute pancreatitis?

    <p>Serum amylase</p> Signup and view all the answers

    What is the primary reason for the increased urinary excretion of amylase in acute pancreatitis?

    <p>The amylase enzyme is released from the damaged pancreatic acinar cells into the bloodstream and is then filtered by the kidneys.</p> Signup and view all the answers

    Which of the following is the most predominant pancreatic amylase isoenzyme in acute pancreatitis?

    <p>Isoenzyme P3</p> Signup and view all the answers

    Where is Gamma Glutamyl Transamine Peptidase/Transferase (GGT) primarily located?

    <p>Hepatic cells</p> Signup and view all the answers

    What is the diagnostic significance of Gamma Glutamyl Transamine Peptidase/Transferase (GGT)?

    <p>Sensitive indicator of alcoholism</p> Signup and view all the answers

    Which enzyme is secreted by the liver and reflects synthetic function rather than hepatocyte injury?

    <p>Pseudocholinesterase (PChE)</p> Signup and view all the answers

    What is the primary function of Aspartate Aminotransferase (AST)?

    <p>Reflects synthetic function of the liver</p> Signup and view all the answers

    What is the diagnostic significance of Alanine Aminotransferase (ALT) among hepatobiliary disorders?

    <p>Increased in pancreatitis</p> Signup and view all the answers

    What is the primary effect of elevated levels of Aspartate Aminotransferase (AST) and Alanine Aminotransferase (ALT)?

    <p>Implies liver injury or damage</p> Signup and view all the answers

    What is the primary characteristic that defines enzymes?

    <p>They hasten chemical reactions in organic matter</p> Signup and view all the answers

    What happens to the reaction rate when the substrate concentration reaches a maximal value?

    <p>The reaction rate remains constant</p> Signup and view all the answers

    Which factor affects enzyme reactions by being nonprotein entities that must bind to particular enzymes before a reaction occurs?

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

    In enzyme kinetics, what is the role of coenzymes?

    <p>Act as substrates for the enzymes</p> Signup and view all the answers

    What is the primary outcome of increasing enzyme concentration in a reaction?

    <p>Increased reaction rate due to more substrate binding</p> Signup and view all the answers

    Which term describes the situation when substrate concentration surpasses enzyme availability, resulting in a constant reaction rate?

    <p><em>Enzyme saturation</em></p> Signup and view all the answers

    What happens when an uncompetitive inhibitor binds to the enzyme-substrate complex?

    <p>More ES complexes are formed and inhibition increases</p> Signup and view all the answers

    At what temperature is the denaturation of enzymes usually significant?

    <p>40°C-50°C</p> Signup and view all the answers

    What is the effect of extreme pH levels on enzymes?

    <p>Denaturation or structural changes</p> Signup and view all the answers

    What does fractionating isoenzymes help in enhancing?

    <p>Total enzyme activity</p> Signup and view all the answers

    What is the significance of the temperature coefficient (Q10) in enzyme activity?

    <p>It increases enzyme activity with temperature rise</p> Signup and view all the answers

    In which pH range do most physiological reactions occur?

    <p>7-8</p> Signup and view all the answers

    According to the Lock and Key Theory proposed by Emil Fisher, what is the key analogy referring to?

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

    Which type of enzymatic reaction follows a rate that is directly proportional to the substrate concentration?

    <p>First-order reaction</p> Signup and view all the answers

    What is the primary advantage of using a continuous monitoring/kinetic assay method over a fixed-time method for measuring enzyme activity?

    <p>It allows for real-time monitoring of the reaction</p> Signup and view all the answers

    Which type of enzyme specificity is exhibited when an enzyme reacts with specific chemical bonds?

    <p>Bond specificity</p> Signup and view all the answers

    According to the Induced Fit Theory proposed by Daniel Koshland, what happens when a substrate binds to an enzyme?

    <p>The enzyme's active site changes shape to fit the substrate</p> Signup and view all the answers

    Which of the following methods of measuring enzyme activity involves determining the change in coenzyme concentration?

    <p>All of the above</p> Signup and view all the answers

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