Electrolyte imbalance MCQs With Answer

Electrolyte imbalance MCQs With Answer is a focused study resource for B. Pharm students covering common and complex electrolyte disorders, mechanisms, diagnostics, and pharmacologic management. This introduction highlights core topics such as sodium, potassium, calcium, magnesium, phosphate disturbances, acid–base interactions, ECG changes, and drug-induced electrolyte shifts. Questions emphasize pathophysiology, laboratory interpretation, therapeutic principles, and important formulas relevant to clinical pharmacy practice. Ideal for exam preparation and practical understanding, these MCQs integrate renal physiology, diuretics, endocrine influences, and replacement strategies to build decision-making skills. Now let’s test your knowledge with 50 MCQs on this topic.

Q1. Which of the following is the normal serum sodium reference range?

• 135–145 mEq/L
• 3.5–5.0 mEq/L
• 8.4–10.2 mg/dL
• 1.5–2.5 mEq/L

Correct Answer: 135–145 mEq/L

Q2. The most common cause of hospital-acquired hyponatremia is:

• Syndrome of inappropriate antidiuretic hormone secretion (SIADH)
• Excessive dietary sodium intake
• Acute phosphate loading
• Hyperaldosteronism

Correct Answer: Syndrome of inappropriate antidiuretic hormone secretion (SIADH)

Q3. Which formula is used to estimate sodium correction in hyperglycemia?

• Corrected Na+ = measured Na+ + 1.6 mEq/L per 100 mg/dL glucose above 100
• Corrected Na+ = measured Na+ − 2.0 mEq/L per 100 mg/dL glucose above 100
• Corrected Na+ = measured Na+ × (glucose/100)
• Corrected Na+ = measured Na+ + 10 mEq/L

Correct Answer: Corrected Na+ = measured Na+ + 1.6 mEq/L per 100 mg/dL glucose above 100

Q4. Rapid correction of chronic hyponatremia risks causing:

• Osmotic demyelination syndrome
• Acute tubular necrosis
• Hypokalemic paralysis
• Nephrogenic diabetes insipidus

Correct Answer: Osmotic demyelination syndrome

Q5. First-line emergency treatment for severe symptomatic hyperkalemia (with ECG changes) is:

• IV calcium gluconate to stabilize the myocardium
• Oral sodium polystyrene sulfonate only
• IV magnesium sulfate
• IV phosphate

Correct Answer: IV calcium gluconate to stabilize the myocardium

Q6. Which intervention shifts potassium intracellularly acutely?

• IV insulin with dextrose
• IV calcium to stabilize membranes
• Oral potassium chloride
• Sodium bicarbonate restriction

Correct Answer: IV insulin with dextrose

Q7. A classic ECG change in hypokalemia is:

• Prominent U waves
• Peaked T waves
• Shortened QT interval
• Brugada pattern

Correct Answer: Prominent U waves

Q8. Thiazide diuretics most commonly cause which electrolyte disturbance?

• Hyponatremia and hypercalcemia
• Hyperkalemia and hypocalcemia
• Hypermagnesemia
• Hyperphosphatemia

Correct Answer: Hyponatremia and hypercalcemia

Q9. Loop diuretics typically cause:

• Hypokalemia, hypocalcemia, and metabolic alkalosis
• Hyperkalemia and metabolic acidosis
• Hypernatremia and hypermagnesemia
• Hypophosphatemia only

Correct Answer: Hypokalemia, hypocalcemia, and metabolic alkalosis

Q10. Which drug can cause hyperkalemia by inhibiting aldosterone-mediated K+ secretion?

• Spironolactone
• Furosemide
• Hydrochlorothiazide
• Loop diuretic ethacrynic acid

Correct Answer: Spironolactone

Q11. Hypomagnesemia commonly results in which of the following?

• Refractory hypokalemia and increased risk of arrhythmias
• Hypercalcemia and sedation
• Decreased PTH secretion leading to hyperphosphatemia
• Nephrogenic diabetes insipidus

Correct Answer: Refractory hypokalemia and increased risk of arrhythmias

Q12. The most reliable laboratory measure of total body calcium is:

• Ionized calcium for physiologic activity; total calcium is affected by albumin
• Total calcium only
• Serum phosphate
• Urinary calcium excretion

Correct Answer: Ionized calcium for physiologic activity; total calcium is affected by albumin

Q13. Which condition typically presents with corrected QT prolongation and tetany?

• Hypocalcemia
• Hypercalcemia
• Hypokalemia
• Hypermagnesemia

Correct Answer: Hypocalcemia

Q14. Rapid IV infusion of calcium in patients on digoxin requires caution because it may:

• Precipitate arrhythmias
• Cause hypernatremia
• Worsen hyponatremia
• Induce neuroleptic malignant syndrome

Correct Answer: Precipitate arrhythmias

Q15. Pseudohyponatremia occurs when:

• Lab measures sodium low due to hyperlipidemia or hyperproteinemia with normal plasma osmolality
• Serum sodium is low because of true water excess
• There is hyperglycemia causing dilutional hyponatremia
• Renal salt wasting is present

Correct Answer: Lab measures sodium low due to hyperlipidemia or hyperproteinemia with normal plasma osmolality

Q16. The anion gap is calculated as Na+ − (Cl− + HCO3−). An increased anion gap suggests:

• Accumulation of unmeasured anions such as lactate or ketoacids
• Hyperchloremic metabolic acidosis
• Primary respiratory acidosis
• Mild dehydration only

Correct Answer: Accumulation of unmeasured anions such as lactate or ketoacids

Q17. In metabolic acidosis, potassium shifts in which direction intracellularly and why?

• Out of cells due to H+ entering cells and exchanging with K+
• Into cells due to increased Na+/K+ ATPase activity
• No shift occurs
• Into cells due to insulin-mediated uptake

Correct Answer: Out of cells due to H+ entering cells and exchanging with K+

Q18. Which phosphate disturbance is commonly seen after refeeding a malnourished patient?

• Hypophosphatemia due to intracellular uptake during carbohydrate refeeding
• Hyperphosphatemia due to renal failure only
• Stable phosphate levels unaffected by refeeding
• Hyperphosphatemia due to increased dietary intake

Correct Answer: Hypophosphatemia due to intracellular uptake during carbohydrate refeeding

Q19. Which of the following drugs can cause SIADH leading to hyponatremia?

• Carbamazepine
• Metformin
• Hydrochlorothiazide only
• Allopurinol

Correct Answer: Carbamazepine

Q20. The safe maximum recommended rate for correcting chronic hyponatremia is approximately:

• 8–10 mEq/L in 24 hours
• 20–24 mEq/L in 4 hours
• Increase to normal within 6 hours
• No limit; correct as fast as possible

Correct Answer: 8–10 mEq/L in 24 hours

Q21. Which electrolyte abnormality is classically associated with severe pancreatitis?

• Hypocalcemia due to saponification
• Hypernatremia due to fluid loss
• Hypermagnesemia due to release from cells
• Hyperphosphatemia due to cell lysis

Correct Answer: Hypocalcemia due to saponification

Q22. Which is an intracellular cation that is crucial for ATP function and often low in chronic alcoholism?

• Magnesium
• Sodium
• Chloride
• Calcium

Correct Answer: Magnesium

Q23. A patient with metabolic alkalosis will have which expected potassium change?

• Hypokalemia due to intracellular shift of K+
• Hyperkalemia due to H+ shifts out
• No change in potassium
• Transient hyperphosphatemia

Correct Answer: Hypokalemia due to intracellular shift of K+

Q24. Which condition causes hypertension with hypokalemia and metabolic alkalosis due to excess mineralocorticoid activity?

• Primary hyperaldosteronism (Conn’s syndrome)
• SIADH
• Liddle syndrome
• Gitelman syndrome

Correct Answer: Primary hyperaldosteronism (Conn’s syndrome)

Q25. Liddle syndrome is characterized by:

• Increased ENaC activity causing hypertension and hypokalemia
• Loss of ENaC causing hyperkalemia
• Loop diuretic use only
• Syndrome of salt wasting and hypotension

Correct Answer: Increased ENaC activity causing hypertension and hypokalemia

Q26. Which laboratory parameter helps distinguish between renal and extrarenal causes of potassium loss?

• Urinary potassium excretion
• Serum chloride level only
• Serum calcium level
• Serum amylase

Correct Answer: Urinary potassium excretion

Q27. In chronic kidney disease, the typical phosphate and calcium pattern is:

• Hyperphosphatemia and hypocalcemia due to reduced phosphate excretion and low calcitriol
• Hypophosphatemia and hypercalcemia
• No change in phosphate or calcium
• Isolated hypocalcemia only

Correct Answer: Hyperphosphatemia and hypocalcemia due to reduced phosphate excretion and low calcitriol

Q28. The treatment of choice for severe symptomatic hypocalcemia is:

• IV calcium gluconate
• Oral calcium carbonate only
• IV potassium phosphate
• IV magnesium sulfate only

Correct Answer: IV calcium gluconate

Q29. Which electrolyte disturbance can cause tetany, paresthesias, and positive Chvostek and Trousseau signs?

• Hypocalcemia
• Hypernatremia
• Hyperkalemia
• Hypermagnesemia

Correct Answer: Hypocalcemia

Q30. Which medication can cause hypermagnesemia, especially in renal failure?

• Magnesium-containing antacids or laxatives
• Loop diuretics
• Thiazide diuretics
• Calcium channel blockers

Correct Answer: Magnesium-containing antacids or laxatives

Q31. Which electrolyte abnormality prolongs the PR and QRS intervals and can cause hypotension in severe cases?

• Hypermagnesemia
• Hypokalemia
• Hypocalcemia
• Hypernatremia

Correct Answer: Hypermagnesemia

Q32. Which is the most appropriate initial fluid for treating hypovolemic hypernatremia?

• Isotonic saline (0.9% NaCl) to restore volume, then hypotonic fluids
• Hypertonic saline immediately
• Oral phosphate solution
• Pure dextrose 5% only

Correct Answer: Isotonic saline (0.9% NaCl) to restore volume, then hypotonic fluids

Q33. Which clinical feature is most specific for hyperkalemia?

• Peaked T waves on ECG
• U waves on ECG
• Positive Chvostek sign
• Nephrolithiasis

Correct Answer: Peaked T waves on ECG

Q34. Sodium polystyrene sulfonate (Kayexalate) reduces potassium by which mechanism?

• Exchange of sodium for potassium in the colon with fecal excretion
• Increasing renal potassium excretion directly
• Stimulating intracellular uptake of potassium by insulin-like action
• Binding potassium in the bloodstream directly

Correct Answer: Exchange of sodium for potassium in the colon with fecal excretion

Q35. Which of the following causes hypernatremia due to water loss with preserved sodium?

• Central diabetes insipidus
• Syndrome of inappropriate ADH
• Primary polydipsia
• Hyperaldosteronism

Correct Answer: Central diabetes insipidus

Q36. In which disorder is hypokalemia associated with normotension and hypocalciuria?

• Gitelman syndrome
• Bartter syndrome
• Liddle syndrome
• Primary hyperaldosteronism

Correct Answer: Gitelman syndrome

Q37. Which lab finding suggests SIADH rather than hypovolemic hyponatremia?

• Low serum osmolality with inappropriately concentrated urine (high urine osmolality)
• High BUN and creatinine with low urine sodium
• Hypernatremia with polyuria
• Low urine osmolality with high serum osmolality

Correct Answer: Low serum osmolality with inappropriately concentrated urine (high urine osmolality)

Q38. Which electrolyte abnormality is commonly associated with prolonged use of proton pump inhibitors?

• Hypomagnesemia
• Hyperkalemia
• Hyperphosphatemia
• Hypercalcemia

Correct Answer: Hypomagnesemia

Q39. The effect of insulin on potassium is mediated primarily by:

• Stimulation of Na+/K+ ATPase, driving K+ into cells
• Inhibition of aldosterone release
• Direct renal potassium excretion
• Blocking ENaC channels

Correct Answer: Stimulation of Na+/K+ ATPase, driving K+ into cells

Q40. Which clinical scenario most likely causes hyperphosphatemia?

• Tumor lysis syndrome
• Prolonged fasting without refeeding
• Diuretic-induced hypovolemia
• Thiazide therapy

Correct Answer: Tumor lysis syndrome

Q41. Correct management of severe symptomatic hypophosphatemia includes:

• IV or oral phosphate replacement based on severity and symptoms
• Immediate high-dose IV calcium only
• Restriction of dietary phosphate without replacement
• Loop diuretic administration

Correct Answer: IV or oral phosphate replacement based on severity and symptoms

Q42. Which electrolyte imbalance is most associated with prolonged use of amphotericin B?

• Hypokalemia and hypomagnesemia due to renal tubular toxicity
• Hyperkalemia only
• Hypermagnesemia only
• Hyponatremia due to SIADH

Correct Answer: Hypokalemia and hypomagnesemia due to renal tubular toxicity

Q43. Which of the following is a common lab clue for hyperosmolar hypernatremia?

• Elevated serum osmolality with high sodium
• Low serum osmolality with low sodium
• Normal serum osmolality with low sodium
• High urine osmolality with low sodium intake

Correct Answer: Elevated serum osmolality with high sodium

Q44. Which acid-base disturbance shifts potassium out of cells and may raise serum potassium?

• Metabolic acidosis
• Metabolic alkalosis
• Respiratory alkalosis
• Chronic respiratory alkalosis only

Correct Answer: Metabolic acidosis

Q45. In a patient with hyperkalemia, which therapy increases urinary potassium excretion by increasing distal sodium delivery?

• Loop diuretics (e.g., furosemide)
• Calcium channel blockers
• IV calcium gluconate
• Beta-blockers

Correct Answer: Loop diuretics (e.g., furosemide)

Q46. Which of the following best describes “non-anion gap metabolic acidosis” causes?

• Loss of bicarbonate or failure to excrete chloride (e.g., diarrhea, renal tubular acidosis)
• Accumulation of lactate or ketoacids
• Primary respiratory alkalosis
• Excess aldosterone activity

Correct Answer: Loss of bicarbonate or failure to excrete chloride (e.g., diarrhea, renal tubular acidosis)

Q47. Which electrolyte disturbance is most likely to produce muscle cramps, tetany, and seizures if severe?

• Hypocalcemia
• Hypernatremia
• Hypercalcemia
• Hypermagnesemia

Correct Answer: Hypocalcemia

Q48. Which test helps assess total body sodium status clinically?

• Blood pressure, orthostatic vitals, and assessment of volume status; urinary sodium may help
• Serum magnesium alone
• Serum creatine kinase
• Serum amylase

Correct Answer: Blood pressure, orthostatic vitals, and assessment of volume status; urinary sodium may help

Q49. Which drug interaction increases risk of hyperkalemia when combined with ACE inhibitors?

• Potassium-sparing diuretics (e.g., spironolactone)
• Loop diuretics
• Thiazide diuretics
• Mannitol

Correct Answer: Potassium-sparing diuretics (e.g., spironolactone)

Q50. Which monitoring parameter is most important when administering IV potassium chloride for hypokalemia?

• Cardiac rhythm and serum potassium levels
• Serum albumin only
• Serum magnesium only
• Urine specific gravity only

Correct Answer: Cardiac rhythm and serum potassium levels

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