ACIDOSIS AND ALKALOSIS MCQs | MCQ Quiz | OmpathStudy Kenya

Question 1

What is the normal pH range of human blood?

Accepted Answer

7.35-7.45 — Blood pH is tightly regulated within a narrow range of 7.35 to 7.45. Even slight deviations from this range can have serious health consequences affecting various physiological processes.

Question 2

A patient with chronic obstructive pulmonary disease (COPD) has ABG results showing pH 7.28, PaCO2 58 mmHg, and HCO3- 26 mEq/L. What is the primary acid-base disorder?

Accepted Answer

Respiratory acidosis — The pH is low (acidosis), PaCO2 is elevated ( 45 mmHg), and HCO3- is normal. This indicates respiratory acidosis caused by inadequate ventilation and CO2 retention, typical in COPD.

Question 3

Which buffer system is the PRIMARY extracellular buffer system in the body?

Accepted Answer

Bicarbonate buffer system — The bicarbonate buffer system (H2CO3/HCO3-) is the primary extracellular buffer system, particularly in blood plasma, maintaining pH within the normal range of 7.35-7.45.

Question 4

A diabetic patient presents with rapid, deep breathing (Kussmaul respirations). Which acid-base disorder is this compensatory mechanism addressing?

Accepted Answer

Metabolic acidosis — Kussmaul respirations (rapid, deep breathing) represent respiratory compensation for metabolic acidosis. The body increases ventilation to eliminate CO2, reducing carbonic acid and helping raise blood pH.

Question 5

What is the normal range for arterial PaCO2?

Accepted Answer

35-45 mmHg — Normal arterial PaCO2 is 35-45 mmHg. Values above 45 mmHg indicate respiratory acidosis, while values below 35 mmHg indicate respiratory alkalosis.

Question 6

A patient with severe vomiting develops metabolic alkalosis. Which mechanism explains this?

Accepted Answer

Loss of gastric acid (HCl) — Vomiting causes loss of gastric acid (HCl), leading to metabolic alkalosis due to the loss of hydrogen ions and relative excess of bicarbonate in the blood.

Question 7

What is the normal range for serum bicarbonate (HCO3-)?

Accepted Answer

22-26 mEq/L — Normal serum bicarbonate is 22-26 mEq/L. Values above 26 mEq/L indicate metabolic alkalosis, while values below 22 mEq/L indicate metabolic acidosis.

Question 8

Which enzyme in renal tubular cells catalyzes the reaction between CO2 and water to form carbonic acid?

Accepted Answer

Carbonic anhydrase — Carbonic anhydrase catalyzes the reversible reaction between CO2 and water to form carbonic acid (H2CO3), which then dissociates into H+ and HCO3-, playing a crucial role in renal acid-base regulation.

Question 9

A patient has ABG results: pH 7.50, PaCO2 30 mmHg, HCO3- 23 mEq/L. What is the diagnosis?

Accepted Answer

Respiratory alkalosis — The pH is high (alkalosis), PaCO2 is low (<35 mmHg), and HCO3- is normal. This indicates respiratory alkalosis caused by hyperventilation and excessive CO2 elimination.

Question 10

What is the formula for calculating anion gap?

Accepted Answer

Na+ - (Cl- + HCO3-) — Anion gap is calculated as Na+ - (Cl- + HCO3-). The normal range is typically 8-12 mEq/L. An increased anion gap suggests metabolic acidosis with unmeasured anions.

Question 11

Which condition is characterized by an increased anion gap metabolic acidosis?

Accepted Answer

Diabetic ketoacidosis — Diabetic ketoacidosis causes increased anion gap metabolic acidosis due to accumulation of unmeasured ketone bodies (β-hydroxybutyrate and acetoacetate), which are acids not measured in routine electrolyte panels.

Question 12

A patient at high altitude develops dizziness and tingling in the extremities. Which acid-base disorder is most likely?

Accepted Answer

Respiratory alkalosis — High altitude causes hyperventilation (to compensate for low oxygen), leading to respiratory alkalosis. Symptoms include dizziness, tingling in extremities, and muscle cramps due to excessive CO2 elimination.

Question 13

In the proximal tubule, hydrogen ions are secreted into the tubular lumen primarily in exchange for which ion?

Accepted Answer

Sodium (Na+) — In the proximal tubule, hydrogen ions are secreted into the tubular lumen by specialized transporters primarily in exchange for sodium ions through Na+/H+ exchangers.

Question 14

Which pharmacological agent inhibits carbonic anhydrase and promotes bicarbonate excretion?

Accepted Answer

Acetazolamide — Acetazolamide inhibits carbonic anhydrase, preventing bicarbonate reabsorption in the kidneys and promoting its excretion, leading to metabolic acidosis correction in conditions like metabolic alkalosis.

Question 15

A patient with lactic acidosis due to septic shock would most likely present with which type of acid-base disorder?

Accepted Answer

Metabolic acidosis with increased anion gap — Lactic acidosis from tissue hypoperfusion in septic shock causes metabolic acidosis with increased anion gap due to accumulation of lactate, an unmeasured anion.

Question 16

What is the primary role of hemoglobin in acid-base balance?

Accepted Answer

Acts as intracellular protein buffer binding hydrogen ions — Hemoglobin acts as an intracellular protein buffer by binding with hydrogen ions, helping prevent large fluctuations in pH within red blood cells and contributing to overall buffering capacity.

Question 17

A patient with severe diarrhea develops metabolic acidosis. What is the mechanism?

Accepted Answer

Loss of bicarbonate-rich intestinal fluids — Severe diarrhea causes loss of bicarbonate-rich intestinal fluids, resulting in metabolic acidosis due to decreased bicarbonate levels in the blood without an increased anion gap.

Question 18

Which hormone promotes sodium reabsorption and can indirectly influence pH regulation?

Accepted Answer

Aldosterone — Aldosterone promotes reabsorption of sodium and bicarbonate ions in the kidneys, leading to increased blood pH and indirectly influencing acid-base regulation.

Question 19

A patient receives excessive intravenous bicarbonate. Which acid-base disorder will likely develop?

Accepted Answer

Metabolic alkalosis — Excessive bicarbonate intake causes metabolic alkalosis due to an excess of bicarbonate in the blood, increasing pH above the normal range.

Question 20

What compensatory mechanism does the body employ in metabolic alkalosis?

Accepted Answer

Decreased ventilation to retain CO2 — In metabolic alkalosis, the respiratory system compensates by decreasing ventilation rate to retain CO2, increasing carbonic acid levels and thereby lowering blood pH toward normal.

Question 21

Which buffer system is most important in regulating intracellular pH and urine pH?

Accepted Answer

Phosphate buffer system — The phosphate buffer system (HPO4²-/H2PO4-) plays a significant role in buffering intracellular fluids and urine, accepting or donating hydrogen ions depending on pH.

Question 22

A patient with anxiety disorder hyperventilates during a panic attack. What immediate acid-base change occurs?

Accepted Answer

Respiratory alkalosis — Hyperventilation during anxiety causes excessive elimination of CO2, leading to respiratory alkalosis characterized by decreased PaCO2 and increased pH.

Question 23

What is the normal range for the anion gap?

Accepted Answer

8-12 mEq/L — The normal anion gap is typically 8-12 mEq/L. Values greater than 12 mEq/L suggest metabolic acidosis due to unmeasured anions like lactate, ketones, or toxins.

Question 24

Which clinical finding is characteristic of severe metabolic acidosis?

Accepted Answer

Kussmaul respirations — Kussmaul respirations (rapid, deep breathing) are characteristic of severe metabolic acidosis, representing the body's attempt to compensate by eliminating CO2 and raising pH.

Question 25

A patient with chronic kidney disease cannot excrete hydrogen ions effectively. Which acid-base disorder develops?

Accepted Answer

Metabolic acidosis — Renal failure impairs the kidneys' ability to excrete hydrogen ions and generate bicarbonate, leading to metabolic acidosis due to accumulation of acids.

Question 26

What is the purpose of calculating the delta gap?

Accepted Answer

Assess coexistence of multiple acid-base disorders — Delta gap is calculated as (observed AG - 12) and assesses the coexistence of multiple acid-base disorders. A positive delta gap suggests metabolic alkalosis in addition to metabolic acidosis.

Question 27

Which medication is commonly used to treat severe metabolic acidosis by acting as a buffer?

Accepted Answer

Sodium bicarbonate — Sodium bicarbonate acts as a buffer by accepting hydrogen ions, thereby increasing blood pH in severe metabolic acidosis, though its use has potential complications.

Question 28

A patient with hyperaldosteronism develops which acid-base disorder?

Accepted Answer

Metabolic alkalosis — Hyperaldosteronism causes excessive sodium and bicarbonate reabsorption in the kidneys, leading to metabolic alkalosis due to increased bicarbonate levels in blood.

Question 29

What happens to potassium levels in metabolic acidosis?

Accepted Answer

Hyperkalemia due to K+ shift out of cells — In metabolic acidosis, hydrogen ions move into cells in exchange for potassium moving out, leading to hyperkalemia (increased serum potassium levels).

Question 30

Which condition causes respiratory acidosis due to respiratory depression?

Accepted Answer

Opioid overdose — Opioid overdose causes respiratory depression, leading to inadequate ventilation, CO2 retention, and respiratory acidosis due to decreased elimination of carbon dioxide.

Question 31

In the kidneys, hydrogen ions are excreted in urine buffered primarily by which substances?

Accepted Answer

Phosphate and ammonia — Hydrogen ions are excreted in urine buffered by phosphate and ammonia (NH3/NH4+), allowing the kidneys to eliminate acid while conserving bicarbonate for the extracellular fluid.

Question 32

A patient with salicylate (aspirin) toxicity initially develops which acid-base disorder?

Accepted Answer

Respiratory alkalosis initially — Salicylate toxicity initially causes respiratory alkalosis by directly stimulating the respiratory center, leading to hyperventilation and CO2 elimination, though metabolic acidosis may develop later.

Question 33

What is the primary advantage of using loop diuretics like furosemide in treating metabolic alkalosis?

Accepted Answer

They promote urinary excretion of bicarbonate — Loop diuretics like furosemide promote urinary excretion of bicarbonate ions, helping correct metabolic alkalosis by reducing blood bicarbonate concentration.

Question 34

Which acid-base parameter reflects the metabolic component?

Accepted Answer

HCO3 — Bicarbonate (HCO3-) reflects the metabolic component of acid-base balance. Normal levels are 22-26 mEq/L. Elevated HCO3- indicates metabolic alkalosis; decreased indicates metabolic acidosis.

Question 35

A patient with methanol poisoning would present with which type of metabolic acidosis?

Accepted Answer

Increased anion gap — Methanol poisoning causes increased anion gap metabolic acidosis due to accumulation of formic acid and other toxic metabolites, which are unmeasured anions.

Question 36

What compensatory mechanism does the kidney employ in respiratory acidosis?

Accepted Answer

Increase H+ secretion and bicarbonate generation — In respiratory acidosis, kidneys compensate by increasing hydrogen ion secretion and generating additional bicarbonate ions, helping to raise blood pH toward normal over several days.

Question 37

Which symptom is characteristic of respiratory alkalosis?

Accepted Answer

Tingling in extremities and muscle cramps — Respiratory alkalosis causes tingling in the extremities, muscle cramps, and dizziness due to decreased CO2 levels and alkaline pH affecting nerve and muscle function.

Question 38

What is the relationship between serum osmolality and metabolic acidosis diagnosis?

Accepted Answer

Increased osmolal gap suggests toxic alcohols — An increased osmolal gap in metabolic acidosis suggests the presence of osmotically active substances like ethanol, methanol, or ethylene glycol, helping differentiate causes of acidosis.

Question 39

When would hemodialysis or continuous renal replacement therapy (CRRT) be indicated for acid-base disorders?

Accepted Answer

Severe metabolic acidosis when other treatments fail — Hemodialysis or CRRT may be necessary in severe cases of metabolic acidosis when other treatments fail, to directly remove accumulated acids and correct life-threatening acid-base imbalances.

Question 40

A patient has ABG results: pH 7.32, PaCO2 48 mmHg, HCO3- 18 mEq/L. What type of acid-base disorder is present?

Accepted Answer

Mixed respiratory and metabolic acidosis — The pH is low (acidosis), PaCO2 is elevated (respiratory acidosis), and HCO3- is decreased (metabolic acidosis). Both parameters are abnormal in the same direction, indicating a mixed disorder with both respiratory and metabolic acidosis.

ACIDOSIS AND ALKALOSIS MCQs | MCQ Quiz | OmpathStudy Kenya

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