Clinical Biochemistry: Calcium, Parathyroid Hormone, Vitamin D Quiz

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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?

To determine the difference between measured and unmeasured anions Signup and view all the answers

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

Increases reabsorption of calcium in the kidneys Signup and view all the answers

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

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

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

To regulate the osmotic activity of plasma Signup and view all the answers

What is the primary cause of hyponatremia?

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

What is the primary cause of hyperchloremia?

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

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

Ion-Selective Electrode Signup and view all the answers

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

To serve as the major component of the buffering system in the blood 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?

Ion-Selective Electrode Signup and view all the answers

What is the primary function of magnesium in the body?

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

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

Parathyroid hormone Signup and view all the answers

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

Serum or lithium heparin plasma Signup and view all the answers

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

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

Which hormone is responsible for regulating blood calcium levels?

Parathyroid hormone Signup and view all the answers

What is the typical range for normal plasma osmolality?

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

Which element is not involved in the blood coagulation process?

Potassium Signup and view all the answers

What is used to calculate the Osmolal Gap?

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

Which cation is the most abundant in the extracellular fluid?

Sodium Signup and view all the answers

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

Arginine vasopressin Signup and view all the answers

What enzymatic activity does Aspartate Aminotransferase (AST) have?

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

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

Liver Signup and view all the answers

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

Increased concentration in acute inflammatory conditions Signup and view all the answers

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

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

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

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

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

Liver Signup and view all the answers

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

To convert alanine and α-ketoglutarate into pyruvate and glutamate 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?

To act as a color developer for the spectrophotometric analysis Signup and view all the answers

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

Serum amylase Signup and view all the answers

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

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

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

Isoenzyme P3 Signup and view all the answers

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

Hepatic cells Signup and view all the answers

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

Sensitive indicator of alcoholism Signup and view all the answers

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

Pseudocholinesterase (PChE) Signup and view all the answers

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

Reflects synthetic function of the liver Signup and view all the answers

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

Increased in pancreatitis Signup and view all the answers

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

Implies liver injury or damage Signup and view all the answers

What is the primary characteristic that defines enzymes?

They hasten chemical reactions in organic matter Signup and view all the answers

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

The reaction rate remains constant 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?

Cofactors Signup and view all the answers

In enzyme kinetics, what is the role of coenzymes?

Act as substrates for the enzymes Signup and view all the answers

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

Increased reaction rate due to more substrate binding Signup and view all the answers

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

Enzyme saturation Signup and view all the answers

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

More ES complexes are formed and inhibition increases Signup and view all the answers

At what temperature is the denaturation of enzymes usually significant?

40°C-50°C Signup and view all the answers

What is the effect of extreme pH levels on enzymes?

Denaturation or structural changes Signup and view all the answers

What does fractionating isoenzymes help in enhancing?

Total enzyme activity Signup and view all the answers

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

It increases enzyme activity with temperature rise Signup and view all the answers

In which pH range do most physiological reactions occur?

7-8 Signup and view all the answers

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

The substrate Signup and view all the answers

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

First-order reaction 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?

It allows for real-time monitoring of the reaction Signup and view all the answers

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

Bond specificity 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?

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

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

All of the above Signup and view all the answers