Electrolytes in replacement therapy: Potassium chloride MCQs With Answer

Electrolytes in replacement therapy: Potassium chloride (KCl) is a core topic in B. Pharm pharmacology, therapeutics, and hospital pharmacy. Understanding hypokalemia management, fluid and electrolyte balance, dosage forms (oral and IV), safe infusion rates, drug interactions (ACE inhibitors, ARBs, potassium-sparing diuretics), and ECG changes is essential for rational KCl use. KCl is crucial when chloride depletion or metabolic alkalosis coexists, and careful monitoring of renal function, acid–base status, and serum potassium is mandatory to prevent hyperkalemia and arrhythmias. Learn indications, contraindications, precautions, and clinical pearls like avoiding dextrose during rapid repletion and correcting hypomagnesemia first. Now let’s test your knowledge with 50 MCQs on this topic.

Q1. The primary indication for potassium chloride in electrolyte replacement therapy is:

• Treatment of hypokalemia
• Treatment of hyperkalemia
• Treatment of hypocalcemia

Correct Answer: Treatment of hypokalemia

Q2. Why is potassium chloride preferred over potassium acetate in metabolic alkalosis?

• Chloride helps correct alkalosis by restoring chloride deficit
• Acetate provides additional chloride
• Acetate lowers serum bicarbonate directly
• Chloride increases bicarbonate production

Correct Answer: Chloride helps correct alkalosis by restoring chloride deficit

Q3. Which is the safest maximum peripheral IV infusion rate for KCl in adults without continuous ECG monitoring?

• 10 mEq/hour
• 20 mEq/hour
• 40 mEq/hour
• IV push bolus

Correct Answer: 10 mEq/hour

Q4. Which formulation of potassium chloride is most associated with GI mucosal irritation if improperly used?

• Concentrated oral liquid if undiluted
• Effervescent tablets dissolved in water
• Enteric-coated microencapsulated capsules
• IV KCl diluted in 0.9% NaCl

Correct Answer: Concentrated oral liquid if undiluted

Q5. Which ECG change is most characteristic of hypokalemia?

• Prominent U waves
• Tall peaked T waves
• Prolonged PR interval exclusively
• Delta waves

Correct Answer: Prominent U waves

Q6. Which ECG finding is most characteristic of early hyperkalemia?

• Tall peaked T waves
• ST elevation
• Prominent U waves
• Fixed wide QRS with absent T waves

Correct Answer: Tall peaked T waves

Q7. Before initiating aggressive IV potassium replacement, which prerequisite is most important?

• Confirm adequate urine output
• Administer dextrose 50%
• Start a calcium infusion
• Restrict fluids completely

Correct Answer: Confirm adequate urine output

Q8. Which of the following increases the risk of hyperkalemia when combined with oral KCl?

• ACE inhibitors
• Loop diuretics
• Thiazide diuretics
• Beta-2 agonists

Correct Answer: ACE inhibitors

Q9. In severe hypokalemia requiring central line infusion with continuous ECG monitoring, which rate is commonly acceptable?

• 20 mEq/hour
• 2 mEq/hour
• 5 mEq/hour
• 60 mEq/hour

Correct Answer: 20 mEq/hour

Q10. Which statement about potassium distribution is correct?

• About 98% of total body potassium is intracellular
• About 50% of total body potassium is extracellular
• Most potassium is stored in bone matrix
• Serum potassium directly equals total body potassium stores

Correct Answer: About 98% of total body potassium is intracellular

Q11. Which condition commonly causes renal potassium wasting leading to hypokalemia?

• Loop diuretic therapy
• Acute anuria
• Untreated Addison’s disease
• Rhabdomyolysis

Correct Answer: Loop diuretic therapy

Q12. Which is a key reason to avoid dextrose-only solutions during rapid potassium repletion?

• Dextrose stimulates insulin, shifting potassium into cells
• Dextrose causes osmotic diuresis that retains potassium
• Dextrose raises serum potassium acutely
• Dextrose neutralizes chloride’s effect

Correct Answer: Dextrose stimulates insulin, shifting potassium into cells

Q13. Which drug increases intracellular shift of potassium and may worsen hypokalemia?

• Salbutamol (albuterol)
• Spironolactone
• Lisinopril
• Triamterene

Correct Answer: Salbutamol (albuterol)

Q14. What is the most important first step when hypokalemia is refractory to KCl replacement?

• Correct hypomagnesemia
• Switch to potassium phosphate
• Add dextrose infusion
• Stop monitoring ECG

Correct Answer: Correct hypomagnesemia

Q15. Which situation is a contraindication to potassium chloride supplementation?

• Hyperkalemia
• Chronic diarrhea
• Metabolic alkalosis
• Thiazide-induced hypokalemia

Correct Answer: Hyperkalemia

Q16. Which best describes KCl’s effect on acid–base balance?

• It is acidifying and helps correct metabolic alkalosis
• It is alkalinizing and worsens metabolic alkalosis
• It has no chloride effect
• It directly buffers hydrogen ions

Correct Answer: It is acidifying and helps correct metabolic alkalosis

Q17. Which adverse effect is most associated with rapid IV KCl infusion?

• Fatal cardiac arrhythmias
• Hyponatremic seizures
• Hypocalcemic tetany
• Bronchospasm

Correct Answer: Fatal cardiac arrhythmias

Q18. Oral extended-release KCl tablets should be:

• Swallowed whole without crushing
• Crushed and mixed with applesauce
• Chewed thoroughly to improve absorption
• Dissolved in hot water

Correct Answer: Swallowed whole without crushing

Q19. Which monitoring plan is appropriate during aggressive IV potassium replacement?

• Frequent serum K checks every 2–4 hours with ECG monitoring
• Daily serum K checks only
• No ECG needed if central line is used
• Monitor only urine output

Correct Answer: Frequent serum K checks every 2–4 hours with ECG monitoring

Q20. In diabetic ketoacidosis (DKA), potassium replacement is typically started:

• After initial fluids and once urine output is established
• Only after completing insulin therapy
• Before any fluids are given
• Never, as DKA causes hyperkalemia only

Correct Answer: After initial fluids and once urine output is established

Q21. Which pairing is correct regarding potassium salts and clinical use?

• Potassium acetate: preferred when metabolic acidosis coexists
• Potassium chloride: preferred when metabolic acidosis coexists
• Potassium citrate: preferred in hyperkalemia
• Potassium phosphate: avoid when hypophosphatemia is present

Correct Answer: Potassium acetate: preferred when metabolic acidosis coexists

Q22. Which is a common gastrointestinal adverse effect of oral KCl?

• Esophageal irritation and ulceration
• Steatorrhea
• Gingival hyperplasia
• Pancreatitis

Correct Answer: Esophageal irritation and ulceration

Q23. What is a practical strategy to reduce GI irritation from oral liquid KCl?

• Dilute with sufficient water or juice before administration
• Administer on an empty stomach with hot tea
• Co-administer with calcium carbonate
• Use sublingual administration

Correct Answer: Dilute with sufficient water or juice before administration

Q24. Which situation often presents with pseudohyperkalemia?

• Hemolysis of the blood sample
• Vomiting-induced metabolic alkalosis
• Loop diuretic therapy
• Insulin overdose

Correct Answer: Hemolysis of the blood sample

Q25. Which endocrine disorder predisposes to hyperkalemia, making KCl use risky?

• Untreated Addison’s disease
• Primary hyperaldosteronism
• Hyperthyroidism
• Diabetes insipidus

Correct Answer: Untreated Addison’s disease

Q26. Which statement about potassium and digoxin is correct?

• Hypokalemia increases the risk of digoxin toxicity
• Hyperkalemia reduces the risk of digoxin toxicity
• Potassium has no interaction with digoxin
• Giving KCl always worsens digoxin toxicity

Correct Answer: Hypokalemia increases the risk of digoxin toxicity

Q27. What is the usual maximum concentration of KCl recommended for peripheral IV infusion to reduce phlebitis risk?

• 40 mEq/L
• 100 mEq/L
• 10 mEq/L
• 80 mEq/L

Correct Answer: 40 mEq/L

Q28. Which is an appropriate step when ordering KCl in maintenance fluids?

• Ensure the patient has adequate urine output and stable renal function
• Always add to 5% dextrose only
• Do not account for ongoing losses
• Use undiluted ampoules for faster effect

Correct Answer: Ensure the patient has adequate urine output and stable renal function

Q29. Which combination most increases the risk of life-threatening hyperkalemia?

• KCl plus spironolactone plus ACE inhibitor
• KCl plus loop diuretic
• KCl plus thiazide diuretic
• KCl plus beta-2 agonist

Correct Answer: KCl plus spironolactone plus ACE inhibitor

Q30. Which symptom is commonly associated with significant hypokalemia?

• Muscle weakness and cramps
• Hyperreflexia and tremor
• Paresthesia followed by tetany
• Hypotension with bradycardia only

Correct Answer: Muscle weakness and cramps

Q31. Which electrolyte abnormality must be addressed to prevent refractory ventricular arrhythmias in hypokalemia?

• Hypomagnesemia
• Hypernatremia
• Hypocalcemia
• Hyperphosphatemia

Correct Answer: Hypomagnesemia

Q32. Which set of serum potassium values best defines moderate hypokalemia?

• 3.0–3.4 mEq/L
• 2.0–2.4 mEq/L
• 3.5–5.0 mEq/L
• 5.5–6.0 mEq/L

Correct Answer: 3.0–3.4 mEq/L

Q33. Which is a recognized cause of hypokalemia due to gastrointestinal loss?

• Chronic diarrhea
• Acute urinary retention
• Acute liver failure
• Primary hypothyroidism

Correct Answer: Chronic diarrhea

Q34. Which best explains why vomiting can cause hypokalemia despite gastric fluid being low in potassium?

• Renal potassium wasting due to metabolic alkalosis and volume depletion
• Direct loss of potassium from saliva
• Respiratory alkalosis reduces potassium secretion
• Increased intestinal absorption of chloride

Correct Answer: Renal potassium wasting due to metabolic alkalosis and volume depletion

Q35. Which is a key safety principle for IV KCl administration?

• Never give KCl as IV push
• Give KCl through arterial line for faster action
• Always mix KCl with hypertonic saline
• Use gravity infusion without a pump

Correct Answer: Never give KCl as IV push

Q36. Which patient scenario would most benefit from choosing potassium phosphate instead of KCl?

• Hypokalemia with concurrent hypophosphatemia
• Hypokalemia with metabolic alkalosis
• Hyperkalemia with acidosis
• Hypokalemia with hyperphosphatemia

Correct Answer: Hypokalemia with concurrent hypophosphatemia

Q37. Which lab artifact can falsely elevate measured potassium, requiring repeat testing before withholding KCl?

• Prolonged tourniquet use and fist clenching
• High bilirubin
• Low albumin
• Hypertriglyceridemia

Correct Answer: Prolonged tourniquet use and fist clenching

Q38. Which is true regarding salt substitutes and potassium balance?

• Many salt substitutes contain potassium chloride and can cause hyperkalemia
• Salt substitutes are sodium-only and safe with ACE inhibitors
• Salt substitutes neutralize chloride’s acidifying effect
• Salt substitutes are contraindicated only in hypokalemia

Correct Answer: Many salt substitutes contain potassium chloride and can cause hyperkalemia

Q39. Which of the following is a typical oral dosing approach for treating mild to moderate hypokalemia?

• 20–40 mEq/day in divided doses, adjusted to response
• 200 mEq as a single dose
• 5 mEq/day only
• No oral therapy; IV required for all cases

Correct Answer: 20–40 mEq/day in divided doses, adjusted to response

Q40. Which best describes the relationship between serum and total body potassium?

• Serum potassium may be normal despite significant total body depletion
• Serum potassium always reflects total body stores accurately
• Total body potassium is measured directly in routine labs
• Low serum potassium always indicates low intracellular potassium

Correct Answer: Serum potassium may be normal despite significant total body depletion

Q41. Which commonly used antihypertensive increases potassium retention and requires caution with KCl?

• Losartan
• Amlodipine
• Hydralazine
• Clonidine

Correct Answer: Losartan

Q42. Which is the most appropriate fluid for initial IV KCl dilution in acute hypokalemia without acid–base concerns?

• 0.9% sodium chloride
• Dextrose 5% water (D5W) only
• Hypertonic saline 3%
• Sterile water alone

Correct Answer: 0.9% sodium chloride

Q43. Which condition is associated with transcellular shift causing hyperkalemia, necessitating caution with KCl?

• Metabolic acidosis
• Metabolic alkalosis
• Beta-2 agonist therapy
• Insulin administration

Correct Answer: Metabolic acidosis

Q44. Which clinical sign suggests severe hyperkalemia requiring immediate action (and avoiding KCl)?

• Widened QRS on ECG
• Isolated sinus tachycardia
• Narrow PR interval
• Normal T waves

Correct Answer: Widened QRS on ECG

Q45. Which is a correct counseling point for patients taking oral KCl extended-release?

• A wax-like matrix may appear in stool; this is expected
• Chewing tablets improves absorption
• Take with grapefruit juice to enhance effect
• Stop the drug if stool residue is seen

Correct Answer: A wax-like matrix may appear in stool; this is expected

Q46. Which scenario most warrants telemetry during potassium repletion?

• Infusion rates exceeding 10 mEq/hour
• Oral dosing of 10 mEq daily
• Topical potassium application
• Single 5 mEq IV dose over 1 hour

Correct Answer: Infusion rates exceeding 10 mEq/hour

Q47. Which patient is at highest risk for KCl-induced hyperkalemia?

• Advanced chronic kidney disease with oliguria
• Acute diarrhea with normal renal function
• Thiazide therapy with polyuria
• Postoperative patient on loop diuretics

Correct Answer: Advanced chronic kidney disease with oliguria

Q48. Which is an appropriate clinical objective when choosing KCl over other potassium salts?

• Correct potassium and chloride deficits together
• Provide alkalinization in lactic acidosis
• Correct hypophosphatemia preferentially
• Reduce bicarbonate generation from acetate

Correct Answer: Correct potassium and chloride deficits together

Q49. Which statement about severe tissue breakdown (e.g., rhabdomyolysis) and potassium is correct?

• It can cause hyperkalemia; avoid KCl until potassium is controlled
• It invariably causes hypokalemia requiring aggressive KCl
• It has no effect on potassium balance
• It reduces risk of arrhythmias with KCl infusion

Correct Answer: It can cause hyperkalemia; avoid KCl until potassium is controlled

Q50. Which of the following is a correct pharmacologic principle for potassium chloride therapy?

• Use an infusion pump and verified dilution for all IV KCl doses
• IV push KCl is acceptable in cardiac arrest
• Dextrose-only solutions are preferred for rapid repletion
• No need to recheck potassium after replacement

Correct Answer: Use an infusion pump and verified dilution for all IV KCl doses