Electrolytes in replacement therapy: Calcium gluconate* MCQs With Answer

Electrolytes in replacement therapy: Calcium gluconate is a critical topic for B. Pharm students, bridging pharmacology, therapeutics, and hospital practice. Calcium gluconate is widely used for acute hypocalcemia, cardioprotection in hyperkalemia, reversal of hypermagnesemia, and management of hydrofluoric acid exposure. Understanding mechanism of action, elemental calcium content, dose equivalence (mEq), IV administration rates, compatibility (with phosphate, bicarbonate, and ceftriaxone), and adverse effects like extravasation is essential. You should also know the differences between calcium gluconate vs calcium chloride, ECG effects, monitoring of ionized calcium, and safe use in renal impairment and digoxin exposure. Now let’s test your knowledge with 50 MCQs on this topic.

Q1. What is the primary reason calcium gluconate is given in severe hyperkalemia with ECG changes?

• It directly lowers serum potassium concentration
• It enhances renal potassium excretion within minutes
• It stabilizes the cardiac membrane by raising the threshold potential
• It drives potassium into cells via insulin-like action

Correct Answer: It stabilizes the cardiac membrane by raising the threshold potential

Q2. How much elemental calcium is contained in 10 mL of a 10% calcium gluconate IV solution?

• 93 mg
• 272 mg
• 20 mg
• 135 mg

Correct Answer: 93 mg

Q3. The elemental calcium provided by 10 mL of 10% calcium gluconate corresponds to approximately how many mEq of Ca2+?

• 2.0 mEq
• 4.65 mEq
• 9.3 mEq
• 13.6 mEq

Correct Answer: 4.65 mEq

Q4. Which statement best describes calcium gluconate’s mechanism in hypocalcemic tetany?

• It increases ionized calcium, restoring neuromuscular excitability to normal
• It blocks sodium channels in motor nerves
• It enhances acetylcholine release at the neuromuscular junction
• It inhibits parathyroid hormone secretion

Correct Answer: It increases ionized calcium, restoring neuromuscular excitability to normal

Q5. In acute hyperkalemia with ECG changes, the recommended IV administration of calcium gluconate is best described as:

• Rapid IV push as fast as possible without monitoring
• Slow IV push over 2–5 minutes with continuous ECG monitoring
• Deep intramuscular injection
• Subcutaneous infusion over 12 hours

Correct Answer: Slow IV push over 2–5 minutes with continuous ECG monitoring

Q6. Which is TRUE regarding calcium gluconate versus calcium chloride when given intravenously?

• Calcium gluconate provides more elemental calcium per mL than calcium chloride
• Calcium chloride is less irritating to peripheral veins than calcium gluconate
• Calcium gluconate is safer for peripheral administration than calcium chloride
• Both provide identical elemental calcium per mL

Correct Answer: Calcium gluconate is safer for peripheral administration than calcium chloride

Q7. Which clinical scenario is a standard indication for IV calcium gluconate?

• Hypernatremia with seizures
• Hypermagnesemia causing respiratory depression
• Hypokalemia refractory to potassium
• Hyponatremia with cerebral edema

Correct Answer: Hypermagnesemia causing respiratory depression

Q8. What is the main safety concern when administering calcium gluconate with ceftriaxone in neonates?

• Severe hypoglycemia
• Fatal precipitation of calcium-ceftriaxone complexes
• Methemoglobinemia
• Serotonin syndrome

Correct Answer: Fatal precipitation of calcium-ceftriaxone complexes

Q9. Which electrolyte abnormality most directly reduces ionized calcium by increasing albumin binding?

• Acidosis
• Hypernatremia
• Alkalosis
• Hyperchloremia

Correct Answer: Alkalosis

Q10. For which exposure is topical or intradermal calcium gluconate specifically indicated?

• Hydrochloric acid skin burns
• Hydrofluoric acid skin burns
• Sulfuric acid eye exposure
• Sodium hydroxide ingestion

Correct Answer: Hydrofluoric acid skin burns

Q11. Why should calcium gluconate not be infused through the same line as sodium bicarbonate?

• Risk of severe hemolysis
• Inactivation of bicarbonate
• Precipitation of calcium carbonate
• Formation of free radicals

Correct Answer: Precipitation of calcium carbonate

Q12. Which adverse effect is most associated with rapid IV administration of calcium gluconate?

• Bronchospasm
• Bradycardia and hypotension
• Severe hyperglycemia
• Ototoxicity

Correct Answer: Bradycardia and hypotension

Q13. Which best describes the relationship between 1 mEq of calcium and elemental calcium mass?

• 1 mEq Ca2+ = 40 mg elemental calcium
• 1 mEq Ca2+ = 27.2 mg elemental calcium
• 1 mEq Ca2+ = 20 mg elemental calcium
• 1 mEq Ca2+ = 9.3 mg elemental calcium

Correct Answer: 1 mEq Ca2+ = 20 mg elemental calcium

Q14. In total parenteral nutrition (TPN), which calcium salt is generally preferred to reduce calcium-phosphate precipitation risk?

• Calcium carbonate
• Calcium gluconate
• Calcium chloride
• Calcium acetate

Correct Answer: Calcium gluconate

Q15. Which pair of electrolytes is most prone to form precipitates when mixed in IV solutions?

• Calcium and phosphate
• Sodium and chloride
• Potassium and chloride
• Magnesium and sulfate

Correct Answer: Calcium and phosphate

Q16. Which statement regarding calcium in hyperkalemia is correct?

• It rapidly decreases total body potassium
• It has no effect on cardiac conduction
• It stabilizes myocardial cells but does not lower serum potassium
• It increases renal excretion of potassium within minutes

Correct Answer: It stabilizes myocardial cells but does not lower serum potassium

Q17. Which ECG change is typically associated with hypocalcemia?

• Shortened QT interval
• Peaked T waves
• Prolonged QT interval
• Sine-wave pattern

Correct Answer: Prolonged QT interval

Q18. Which condition warrants caution or avoidance of IV calcium due to arrhythmia risk?

• Active digoxin toxicity
• Hypothyroidism
• Iron deficiency anemia
• Mild dehydration

Correct Answer: Active digoxin toxicity

Q19. Which complication is most likely if calcium gluconate extravasates peripherally?

• Severe hypoglycemia at the site
• Tissue necrosis and calcinosis cutis
• Lipodystrophy
• Raynaud phenomenon

Correct Answer: Tissue necrosis and calcinosis cutis

Q20. Which laboratory parameter most closely correlates with neuromuscular symptoms and should guide acute calcium replacement?

• Total serum calcium (uncorrected)
• Ionized calcium
• Serum albumin only
• Serum phosphate only

Correct Answer: Ionized calcium

Q21. In acute symptomatic hypocalcemia with seizures, the best initial step is:

• Oral calcium carbonate
• IV calcium gluconate bolus followed by infusion
• Magnesium sulfate infusion
• High-dose calcitonin

Correct Answer: IV calcium gluconate bolus followed by infusion

Q22. The normal reference range for total serum calcium in adults is approximately:

• 6–7 mg/dL
• 7.0–8.0 mg/dL
• 8.5–10.5 mg/dL
• 11–13 mg/dL

Correct Answer: 8.5–10.5 mg/dL

Q23. Which is TRUE regarding calcium chloride compared to calcium gluconate?

• Calcium chloride contains about three times more elemental calcium per mL
• Calcium chloride is less likely to cause tissue injury if extravasated
• Calcium chloride is preferred for peripheral IV lines
• Both have identical osmolarity

Correct Answer: Calcium chloride contains about three times more elemental calcium per mL

Q24. In hypermagnesemia from magnesium sulfate overdose, the preferred antidote dose is commonly:

• 10 mL of 10% calcium gluconate IV over 2–5 minutes
• 50 mL of 10% calcium gluconate IV push in 30 seconds
• 1 mL of 10% calcium gluconate IM
• Oral calcium gluconate 1 g

Correct Answer: 10 mL of 10% calcium gluconate IV over 2–5 minutes

Q25. Which ion decreases the risk of symptomatic hypocalcemia when corrected first in refractory cases?

• Potassium
• Magnesium
• Sodium
• Chloride

Correct Answer: Magnesium

Q26. Which route of administration is contraindicated for calcium gluconate due to severe local reactions?

• Intravenous
• Intra-arterial
• Oral
• Topical (for HF burns)

Correct Answer: Intra-arterial

Q27. What is the most appropriate monitoring during IV calcium gluconate administration?

• Continuous ECG and periodic serum ionized calcium
• Peak expiratory flow rate
• Liver enzymes every 5 minutes
• Urinalysis for glucose

Correct Answer: Continuous ECG and periodic serum ionized calcium

Q28. Which combination must be avoided or separated by thorough line flushing to prevent precipitation?

• Calcium gluconate and sodium phosphate
• Calcium gluconate and normal saline
• Calcium gluconate and dextrose 5%
• Calcium gluconate and magnesium sulfate

Correct Answer: Calcium gluconate and sodium phosphate

Q29. Which clinical effect is characteristic of hypercalcemia on ECG?

• Prolonged QT interval
• Shortened QT interval
• Peaked T waves
• ST elevation

Correct Answer: Shortened QT interval

Q30. Which statement about calcium gluconate content is correct?

• 10% solution contains 100 mg/mL elemental calcium
• 10% solution contains 9.3 mg/mL elemental calcium
• 10% solution contains 27.2 mg/mL elemental calcium
• 10% solution contains 4.65 mg/mL elemental calcium

Correct Answer: 10% solution contains 9.3 mg/mL elemental calcium

Q31. Which adverse effect is most likely from chronic excessive calcium and phosphate administration?

• Gout
• Calciphylaxis and soft tissue calcification
• Hemolytic anemia
• Hypokalemia

Correct Answer: Calciphylaxis and soft tissue calcification

Q32. In managing hyperkalemia, calcium gluconate is typically given before which of the following?

• Hemodialysis
• Insulin with dextrose
• Beta-agonist nebulization
• Sodium zirconium cyclosilicate

Correct Answer: Insulin with dextrose

Q33. Which statement best differentiates calcium gluconate from calcium chloride regarding venous irritation?

• Both are non-vesicants and safe peripherally
• Calcium gluconate is less irritating and preferred peripherally
• Calcium gluconate is more irritating than calcium chloride
• Only calcium chloride can be given via central line

Correct Answer: Calcium gluconate is less irritating and preferred peripherally

Q34. Which is a key counseling point for chronic calcium replacement to maintain normal calcium balance?

• Avoid vitamin D to prevent hypercalcemia
• Ensure adequate vitamin D to enhance calcium absorption
• Take calcium only at bedtime
• Avoid all dietary phosphate

Correct Answer: Ensure adequate vitamin D to enhance calcium absorption

Q35. Which patient factor increases risk of hypercalcemia during IV calcium therapy?

• Normal renal function
• Renal impairment
• Hypomagnesemia
• Low phosphate levels

Correct Answer: Renal impairment

Q36. What is the typical onset of cardioprotective effect after IV calcium gluconate in hyperkalemia?

• Immediate to within minutes
• 1–2 hours
• 6–8 hours
• 24 hours

Correct Answer: Immediate to within minutes

Q37. Which statement about mixing calcium with blood products is correct?

• It is safe to infuse calcium in the same line as citrate-anticoagulated blood
• Calcium reverses citrate anticoagulation and should not be co-infused in the same line
• Calcium prevents clotting in transfusion lines
• Calcium has no interaction with citrate

Correct Answer: Calcium reverses citrate anticoagulation and should not be co-infused in the same line

Q38. Which condition often requires aggressive calcium replacement postoperatively?

• Appendectomy
• Parathyroidectomy (hungry bone syndrome)
• Cholecystectomy
• Hernia repair

Correct Answer: Parathyroidectomy (hungry bone syndrome)

Q39. Which laboratory pattern increases risk of calcium-phosphate precipitation in tissues?

• Calcium-phosphate product less than 30 mg²/dL²
• Calcium-phosphate product around 40 mg²/dL²
• Calcium-phosphate product greater than 55 mg²/dL²
• Isolated low chloride

Correct Answer: Calcium-phosphate product greater than 55 mg²/dL²

Q40. Which sign is classic for symptomatic hypocalcemia?

• Trousseau sign
• Kernig sign
• Murphy sign
• McBurney point tenderness

Correct Answer: Trousseau sign

Q41. In total parenteral nutrition, which practice helps minimize Ca–P precipitation?

• Use high solution pH and add phosphate last
• Use lower solution pH, add phosphate first and calcium last, and keep total Ca–P product lower
• Add calcium and phosphate together early during compounding
• Warm the solution to promote dissolution

Correct Answer: Use lower solution pH, add phosphate first and calcium last, and keep total Ca–P product lower

Q42. Which is an appropriate clinical use of IV calcium in calcium channel blocker overdose?

• First-line definitive therapy replacing vasopressors
• Adjunct therapy to improve contractility and blood pressure
• Contraindicated due to arrhythmia risk
• Only topical calcium is useful

Correct Answer: Adjunct therapy to improve contractility and blood pressure

Q43. Which statement about oral versus IV calcium salts is correct?

• Oral calcium gluconate has high elemental calcium compared to carbonate
• Calcium carbonate provides more elemental calcium than calcium gluconate
• IV calcium is preferred for chronic maintenance
• Calcium citrate contains no elemental calcium

Correct Answer: Calcium carbonate provides more elemental calcium than calcium gluconate

Q44. Which best describes the risk of “stone heart” with calcium in digoxin toxicity?

• Well-proven and common
• A theoretical concern; many guidelines advise avoiding calcium if digoxin toxicity is present
• Only occurs with oral calcium
• Only occurs in hypokalemia

Correct Answer: A theoretical concern; many guidelines advise avoiding calcium if digoxin toxicity is present

Q45. Which of the following is NOT a typical adverse effect of IV calcium gluconate?

• Flushing
• Nausea
• Bradycardia with rapid infusion
• Profound neutropenia

Correct Answer: Profound neutropenia

Q46. Which chemical exposure decreases ionized calcium by chelation, potentially requiring calcium administration?

• Hydrogen peroxide
• Ethylenediaminetetraacetic acid (EDTA)
• Acetone
• Benzene

Correct Answer: Ethylenediaminetetraacetic acid (EDTA)

Q47. Which instruction reduces the risk of local injury with peripheral IV calcium gluconate?

• Use a small distal vein and rapid push
• Use a well-functioning large-bore vein and slow infusion
• Give intra-arterially if veins are small
• Dilute in hypertonic saline

Correct Answer: Use a well-functioning large-bore vein and slow infusion

Q48. Which statement best describes ionized calcium?

• It is the protein-bound fraction and biologically inactive
• It is the free, physiologically active fraction of calcium
• It represents stored calcium in bone
• It is only present in intracellular fluid

Correct Answer: It is the free, physiologically active fraction of calcium

Q49. In hyperkalemia, which ECG change most urgently drives the decision to give IV calcium?

• U waves
• Peaked, narrow T waves and/or widening QRS
• Sinus tachycardia
• ST depression

Correct Answer: Peaked, narrow T waves and/or widening QRS

Q50. Which statement about calcium gluconate in electrolyte replacement is most accurate?

• It lowers serum phosphate by direct renal excretion within minutes
• It is primarily used to acutely correct symptomatic hypocalcemia and stabilize cardiac membranes
• It is contraindicated in all patients with renal disease
• It reliably treats chronic calcium deficiency as a sole long-term therapy

Correct Answer: It is primarily used to acutely correct symptomatic hypocalcemia and stabilize cardiac membranes