Lab values are one of the most heavily tested areas in the NCLEX exam. Every nurse must recognize which values are normal, which are critical, and what actions to take when results are abnormal.
This quiz of 100+ NCLEX lab value questions is designed to help you master essential labs — electrolytes, ABGs, hematology, renal, cardiac, and more. Each question includes a rationale, ensuring you understand why an answer is correct.
📋 Normal Lab Values Table (Quick Review)
| Category | Test | Normal Range |
| Electrolytes | Sodium | 135–145 mEq/L |
| Potassium | 3.5–5.0 mEq/L | |
| Calcium | 8.5–10.5 mg/dL | |
| Magnesium | 1.5–2.5 mEq/L | |
| Renal | BUN | 7–20 mg/dL |
| Creatinine | 0.6–1.3 mg/dL | |
| Hematology | Hemoglobin | 12–16 g/dL (female), 14–18 (male) |
| Hematocrit | 37–47% (female), 42–52% (male) | |
| Arterial Blood Gases (ABG) | pH | 7.35–7.45 |
| PaCO₂ | 35–45 mmHg | |
| HCO₃ | 22–26 mEq/L | |
| Cardiac Markers | Troponin I | < 0.04 ng/mL |
| BNP | < 100 pg/mL | |
| Liver Function | ALT | 7–56 U/L |
| AST | 10–40 U/L |
1. A patient’s serum potassium level is 2.9 mEq/L. The nurse should anticipate which complication?
A. Hyperreflexia
B. Cardiac arrhythmias
C. Respiratory acidosis
D. Hypotension
✅ Correct Answer: B. Cardiac arrhythmias
💡 Rationale: Hypokalemia (K⁺ < 3.5) can cause dangerous cardiac arrhythmias and muscle weakness due to impaired electrical activity in myocardial cells.
2. The nurse reviews the ABG results: pH 7.28, PaCO₂ 50 mmHg, HCO₃ 24 mEq/L. What is the interpretation?
A. Respiratory acidosis
B. Metabolic acidosis
C. Respiratory alkalosis
D. Metabolic alkalosis
✅ Correct Answer: A. Respiratory acidosis
💡 Rationale: Low pH (acidosis) with elevated PaCO₂ indicates CO₂ retention — a hallmark of respiratory acidosis, often due to hypoventilation or COPD.
3. Which lab finding indicates dehydration?
A. Low BUN
B. High hematocrit
C. Low specific gravity
D. Decreased sodium
✅ Correct Answer: B. High hematocrit
💡 Rationale: In dehydration, plasma volume decreases, concentrating red blood cells and elevating hematocrit.
4. Normal serum calcium level is:
A. 6–8 mg/dL
B. 8.5–10.5 mg/dL
C. 12–14 mg/dL
D. 10.5–12.5 mg/dL
✅ Correct Answer: B. 8.5–10.5 mg/dL
💡 Rationale: Calcium is vital for nerve transmission and clotting; both hypo- and hypercalcemia can cause severe neuromuscular symptoms.
5. Which result should be reported immediately to the provider?
A. Sodium 138 mEq/L
B. Potassium 5.8 mEq/L
C. Chloride 100 mEq/L
D. Magnesium 2.0 mEq/L
✅ Correct Answer: B. Potassium 5.8 mEq/L
💡 Rationale: Potassium >5.5 mEq/L can cause life-threatening cardiac dysrhythmias and requires urgent evaluation.
6. Which lab value indicates renal impairment?
A. BUN 8 mg/dL
B. Creatinine 2.1 mg/dL
C. Sodium 138 mEq/L
D. Glucose 90 mg/dL
✅ Correct Answer: B. Creatinine 2.1 mg/dL
💡 Rationale: Elevated serum creatinine reflects impaired kidney filtration, commonly seen in renal disease.
7. Which ABG result indicates metabolic alkalosis?
A. pH 7.48, HCO₃ 30 mEq/L
B. pH 7.30, HCO₃ 18 mEq/L
C. pH 7.45, CO₂ 40 mmHg
D. pH 7.36, CO₂ 44 mmHg
✅ Correct Answer: A. pH 7.48, HCO₃ 30 mEq/L
💡 Rationale: Elevated pH and bicarbonate indicate a metabolic cause of alkalosis, such as vomiting or antacid use.
8. A patient receiving diuretics develops muscle cramps. Which lab should be checked first?
A. Sodium
B. Potassium
C. Calcium
D. Phosphate
✅ Correct Answer: B. Potassium
💡 Rationale: Loop and thiazide diuretics increase potassium excretion, leading to hypokalemia-related cramps.
9. Which lab finding confirms hyponatremia?
A. Na⁺ 145 mEq/L
B. Na⁺ 120 mEq/L
C. Na⁺ 140 mEq/L
D. Na⁺ 150 mEq/L
✅ Correct Answer: B. Na⁺ 120 mEq/L
💡 Rationale: Sodium below 135 mEq/L defines hyponatremia, which can cause seizures and neurological changes.
10. A diabetic patient’s fasting glucose is 250 mg/dL. This indicates:
A. Normal result
B. Hypoglycemia
C. Hyperglycemia
D. Impaired fasting tolerance
✅ Correct Answer: C. Hyperglycemia
💡 Rationale: Normal fasting glucose is 70–100 mg/dL. 250 mg/dL suggests poor glycemic control.
11. Which ABG pattern shows metabolic acidosis?
A. pH 7.30, HCO₃ 18 mEq/L
B. pH 7.50, HCO₃ 28 mEq/L
C. pH 7.45, CO₂ 45 mmHg
D. pH 7.36, CO₂ 40 mmHg
✅ Correct Answer: A. pH 7.30, HCO₃ 18 mEq/L
💡 Rationale: Low pH and low bicarbonate reflect metabolic acidosis, often due to DKA or renal failure.
12. Which lab result is consistent with liver disease?
A. ALT 12 U/L
B. AST 15 U/L
C. Bilirubin 2.5 mg/dL
D. Albumin 4.5 g/dL
✅ Correct Answer: C. Bilirubin 2.5 mg/dL
💡 Rationale: Elevated bilirubin indicates impaired hepatic clearance or bile duct obstruction.
13. What is a normal WBC count?
A. 2,000–4,000/mm³
B. 4,000–11,000/mm³
C. 11,000–15,000/mm³
D. 1,000–3,000/mm³
✅ Correct Answer: B. 4,000–11,000/mm³
💡 Rationale: WBCs fight infection; deviations suggest infection or bone marrow disorders.
14. Which electrolyte imbalance is caused by renal failure?
A. Hypokalemia
B. Hyperkalemia
C. Hyponatremia
D. Hypocalcemia
✅ Correct Answer: B. Hyperkalemia
💡 Rationale: The kidneys excrete potassium; failure leads to dangerous elevations.
15. Which lab finding requires immediate follow-up?
A. Glucose 120 mg/dL
B. Sodium 136 mEq/L
C. Calcium 7.0 mg/dL
D. Chloride 102 mEq/L
✅ Correct Answer: C. Calcium 7.0 mg/dL
💡 Rationale: Hypocalcemia can lead to tetany, seizures, and cardiac instability.
16. Which test best reflects nutritional status?
A. Hematocrit
B. Serum albumin
C. BUN
D. Sodium
✅ Correct Answer: B. Serum albumin
💡 Rationale: Albumin decreases in malnutrition and chronic illness, reflecting protein reserves.
17. Which lab abnormality is typical in diabetic ketoacidosis (DKA)?
A. High bicarbonate
B. High pH
C. Low potassium
D. Low pH and low bicarbonate
✅ Correct Answer: D. Low pH and low bicarbonate
💡 Rationale: DKA causes metabolic acidosis due to accumulation of ketone acids.
18. Which value shows anemia?
A. Hemoglobin 13 g/dL
B. Hemoglobin 15 g/dL
C. Hemoglobin 9 g/dL
D. Hemoglobin 16 g/dL
✅ Correct Answer: C. Hemoglobin 9 g/dL
💡 Rationale: Hemoglobin below 12 g/dL (women) or 14 g/dL (men) indicates anemia.
19. Which lab test indicates cardiac muscle damage?
A. AST
B. Troponin I
C. Amylase
D. Bilirubin
✅ Correct Answer: B. Troponin I
💡 Rationale: Elevated troponin I is specific for myocardial infarction.
20. A patient with respiratory alkalosis will likely have which ABG result?
A. pH 7.50, PaCO₂ 30 mmHg
B. pH 7.30, PaCO₂ 50 mmHg
C. pH 7.35, PaCO₂ 45 mmHg
D. pH 7.45, PaCO₂ 40 mmHg
✅ Correct Answer: A. pH 7.50, PaCO₂ 30 mmHg
💡 Rationale: Hyperventilation reduces CO₂, leading to increased pH.
- What is the normal range for serum potassium (K⁺)?
A. 2.5–3.5 mEq/L
B. 3.5–5.0 mEq/L
C. 5.5–6.5 mEq/L
D. 6.0–8.0 mEq/L
✅ Answer: B. 3.5–5.0 mEq/L
Rationale: Potassium regulates cardiac and muscle function. Below 3.5 indicates hypokalemia; above 5.0 suggests hyperkalemia, both potentially life-threatening.
- Which lab value is most critical to monitor for a patient taking digoxin?
A. Sodium
B. Potassium
C. Calcium
D. Chloride
✅ Answer: B. Potassium
Rationale: Hypokalemia increases digoxin toxicity risk, leading to dangerous arrhythmias. Monitoring potassium ensures cardiac safety.
- What is the normal range of serum calcium (Ca²⁺)?
A. 6–8 mg/dL
B. 8.5–10.5 mg/dL
C. 10–12 mg/dL
D. 12–14 mg/dL
✅ Answer: B. 8.5–10.5 mg/dL
Rationale: Calcium supports bone health, nerve transmission, and cardiac function. Deviations may cause muscle cramps or cardiac dysrhythmias.
- What does a high BUN (Blood Urea Nitrogen) indicate?
A. Liver failure
B. Kidney dysfunction or dehydration
C. Hypoglycemia
D. Low protein intake
✅ Answer: B. Kidney dysfunction or dehydration
Rationale: Elevated BUN suggests renal impairment or fluid deficit due to accumulation of nitrogen waste.
- A patient’s serum creatinine is 2.1 mg/dL. What does this imply?
A. Normal renal function
B. Mild dehydration
C. Impaired kidney function
D. Low protein intake
✅ Answer: C. Impaired kidney function
Rationale: Normal creatinine is 0.6–1.2 mg/dL. Elevated levels indicate decreased glomerular filtration and possible renal disease.
26. Which of the following indicates infection?
A. Platelets 150,000/mm³
B. WBC 15,000/mm³
C. Hemoglobin 14 g/dL
D. RBC 5.0 million/mm³
✅ Correct Answer: B. WBC 15,000/mm³
💡 Rationale: WBC >11,000/mm³ indicates an ongoing infection or inflammatory process.
27. Which lab value is abnormally high in dehydration?
A. BUN
B. Sodium
C. Calcium
D. Potassium
✅ Correct Answer: A. BUN
💡 Rationale: Dehydration reduces renal perfusion, increasing BUN due to concentration of nitrogenous wastes.
28. Which electrolyte imbalance is associated with muscle twitching and tetany?
A. Hypercalcemia
B. Hypocalcemia
C. Hypernatremia
D. Hypokalemia
✅ Correct Answer: B. Hypocalcemia
💡 Rationale: Low calcium increases neuromuscular excitability, causing spasms and Chvostek’s sign.
29. A patient’s INR is 4.8 while on warfarin. What should the nurse do?
A. Continue the dose
B. Hold the dose and notify provider
C. Give an extra dose
D. Check potassium
✅ Correct Answer: B. Hold the dose and notify provider
💡 Rationale: Therapeutic INR is 2.0–3.0. INR >4.5 increases bleeding risk and requires immediate attention.
30. Which finding is consistent with hypoglycemia?
A. Glucose 180 mg/dL
B. Glucose 110 mg/dL
C. Glucose 60 mg/dL
D. Glucose 250 mg/dL
✅ Correct Answer: C. Glucose 60 mg/dL
💡 Rationale: Blood glucose <70 mg/dL defines hypoglycemia; symptoms include sweating, tremors, and confusion.
31. Which lab indicates respiratory alkalosis compensation?
A. pH 7.52, HCO₃ 22 mEq/L
B. pH 7.28, HCO₃ 15 mEq/L
C. pH 7.30, HCO₃ 30 mEq/L
D. pH 7.45, HCO₃ 24 mEq/L
✅ Correct Answer: A. pH 7.52, HCO₃ 22 mEq/L
💡 Rationale: Low CO₂ and low bicarbonate show partial compensation of respiratory alkalosis.
32. Which value suggests hypernatremia?
A. Na⁺ 120 mEq/L
B. Na⁺ 130 mEq/L
C. Na⁺ 145 mEq/L
D. Na⁺ 160 mEq/L
✅ Correct Answer: D. Na⁺ 160 mEq/L
💡 Rationale: Serum sodium >145 mEq/L indicates hypernatremia, usually from dehydration or sodium gain.
33. Which test is used to assess blood coagulation in heparin therapy?
A. INR
B. PT
C. aPTT
D. D-dimer
✅ Correct Answer: C. aPTT
💡 Rationale: aPTT monitors the effectiveness and safety of heparin therapy; therapeutic range is 1.5–2.5× normal.
34. Which lab test helps evaluate thyroid function?
A. TSH
B. LDL
C. Troponin
D. AST
✅ Correct Answer: A. TSH
💡 Rationale: Thyroid-stimulating hormone (TSH) regulates T3/T4 secretion; abnormal values indicate thyroid disorders.
35. A patient’s hemoglobin is 7.5 g/dL. What should the nurse anticipate?
A. Increase in oxygen therapy
B. Blood transfusion
C. Discontinue IV fluids
D. Encourage ambulation
✅ Correct Answer: B. Blood transfusion
💡 Rationale: Hgb <8 g/dL requires transfusion to prevent tissue hypoxia.
36. Which lab finding supports hypomagnesemia?
A. Magnesium 1.0 mg/dL
B. Magnesium 2.0 mg/dL
C. Magnesium 2.5 mg/dL
D. Magnesium 3.0 mg/dL
✅ Correct Answer: A. Magnesium 1.0 mg/dL
💡 Rationale: Normal magnesium: 1.5–2.5 mg/dL. Low levels cause tremors and cardiac irritability.
37. Which lab abnormality is common in Addison’s disease?
A. Hypernatremia
B. Hyperkalemia
C. Hypercalcemia
D. Hyperglycemia
✅ Correct Answer: B. Hyperkalemia
💡 Rationale: Addison’s disease causes aldosterone deficiency, leading to sodium loss and potassium retention.
38. A patient’s platelet count is 90,000/mm³. The nurse should:
A. Encourage exercise
B. Avoid IM injections
C. Administer anticoagulants
D. Increase vitamin K intake
✅ Correct Answer: B. Avoid IM injections
💡 Rationale: Platelet count <100,000 increases bleeding risk; avoid invasive procedures.
39. Which electrolyte imbalance is most likely to cause cardiac arrest?
A. Hyperkalemia
B. Hyponatremia
C. Hypocalcemia
D. Hypomagnesemia
✅ Correct Answer: A. Hyperkalemia
💡 Rationale: Potassium imbalance directly affects cardiac conduction and can cause fatal arrhythmias.
40. Which of the following is a normal arterial oxygen level (PaO₂)?
A. 30–50 mmHg
B. 80–100 mmHg
C. 120–150 mmHg
D. 50–70 mmHg
✅ Correct Answer: B. 80–100 mmHg
💡 Rationale: This range represents normal arterial oxygenation; values <80 indicate hypoxemia.
41. A nurse observes Trousseau’s sign. Which lab result is expected?
A. High potassium
B. Low calcium
C. Low sodium
D. High chloride
✅ Correct Answer: B. Low calcium
💡 Rationale: Trousseau’s and Chvostek’s signs are classic indicators of hypocalcemia.
42. The normal range of serum phosphate (PO₄³⁻) is:
A. 1.0–2.0 mg/dL
B. 2.5–4.5 mg/dL
C. 5.0–6.0 mg/dL
D. 0.5–1.5 mg/dL
✅ Correct Answer: B. 2.5–4.5 mg/dL
💡 Rationale: Phosphate supports energy metabolism and bone structure; imbalances affect muscle function.
43. Which test is elevated in pancreatitis?
A. Amylase
B. AST
C. CK-MB
D. LDH
✅ Correct Answer: A. Amylase
💡 Rationale: Amylase and lipase rise during pancreatic inflammation.
44. A patient with chronic kidney disease will likely show:
A. Increased creatinine and BUN
B. Decreased potassium
C. Decreased phosphate
D. Increased sodium
✅ Correct Answer: A. Increased creatinine and BUN
💡 Rationale: Reduced filtration causes accumulation of nitrogenous wastes in blood.
45. Which ABG pattern indicates compensated metabolic acidosis?
A. pH 7.36, CO₂ 30 mmHg, HCO₃ 18 mEq/L
B. pH 7.28, CO₂ 50 mmHg, HCO₃ 25 mEq/L
C. pH 7.52, CO₂ 35 mmHg, HCO₃ 30 mEq/L
D. pH 7.40, CO₂ 40 mmHg, HCO₃ 24 mEq/L
✅ Correct Answer: A. pH 7.36, CO₂ 30 mmHg, HCO₃ 18 mEq/L
💡 Rationale: Normal pH with low HCO₃ and CO₂ shows respiratory compensation for metabolic acidosis.
46. Normal serum chloride range:
A. 70–90 mEq/L
B. 90–110 mEq/L
C. 120–140 mEq/L
D. 60–80 mEq/L
✅ Correct Answer: B. 90–110 mEq/L
💡 Rationale: Chloride helps maintain acid–base balance and hydration.
47. Which lab test monitors long-term glucose control?
A. Fasting glucose
B. HbA1c
C. Random glucose
D. Insulin level
✅ Correct Answer: B. HbA1c
💡 Rationale: HbA1c reflects average blood glucose over 2–3 months; normal <5.7%.
48. Which test is elevated in myocardial infarction within hours?
A. CK-MB
B. Amylase
C. Bilirubin
D. Lipase
✅ Correct Answer: A. CK-MB
💡 Rationale: CK-MB rises within 4–6 hours after cardiac injury.
49. Which lab finding is seen in Cushing’s syndrome?
A. Hyperglycemia
B. Hypokalemia
C. Both A and B
D. Hypocalcemia
✅ Correct Answer: C. Both A and B
💡 Rationale: Cortisol excess raises glucose and lowers potassium.
50. Which lab test evaluates anticoagulant effect of warfarin?
A. aPTT
B. PT/INR
C. Bleeding time
D. D-dimer
✅ Correct Answer: B. PT/INR
💡 Rationale: PT/INR assesses warfarin therapy; therapeutic INR = 2.0–3.0.
51. A patient’s potassium level is 2.8 mEq/L. What complication is most concerning?
A. Muscle weakness
B. Cardiac arrhythmia
C. Constipation
D. Headache
✅ Correct Answer: B. Cardiac arrhythmia
💡 Rationale: Low potassium can lead to life-threatening ventricular arrhythmias.
52. Which lab value indicates renal impairment?
A. Creatinine 1.2 mg/dL
B. BUN 10 mg/dL
C. Creatinine 2.8 mg/dL
D. Sodium 140 mEq/L
✅ Correct Answer: C. Creatinine 2.8 mg/dL
💡 Rationale: Creatinine >1.3 mg/dL indicates kidney dysfunction.
53. Which result supports metabolic alkalosis?
A. pH 7.50, HCO₃ 30
B. pH 7.30, HCO₃ 18
C. pH 7.40, HCO₃ 24
D. pH 7.28, HCO₃ 25
✅ Correct Answer: A. pH 7.50, HCO₃ 30
💡 Rationale: High pH and bicarbonate = metabolic alkalosis.
54. What does elevated troponin suggest?
A. Heart failure
B. Myocardial infarction
C. Renal failure
D. Dehydration
✅ Correct Answer: B. Myocardial infarction
💡 Rationale: Troponin is the most specific cardiac biomarker for myocardial injury.
55. Which lab abnormality requires immediate attention?
A. Sodium 148
B. Potassium 6.5
C. Hemoglobin 12
D. Platelets 160,000
✅ Correct Answer: B. Potassium 6.5
💡 Rationale: Hyperkalemia >6.0 mEq/L can cause fatal cardiac arrest.
56. A diabetic patient’s HbA1c is 9%. What does this indicate?
A. Excellent glucose control
B. Normal range
C. Poor glucose control
D. Recent hypoglycemia
✅ Correct Answer: C. Poor glucose control
💡 Rationale: Target HbA1c for diabetics is <7%; 9% shows chronic hyperglycemia.
57. Which electrolyte helps regulate muscle contraction and cardiac function?
A. Calcium
B. Iron
C. Phosphate
D. Chloride
✅ Correct Answer: A. Calcium
💡 Rationale: Calcium stabilizes cell membranes and controls heart rhythm.
58. Which test monitors heparin therapy?
A. PT
B. INR
C. aPTT
D. D-dimer
✅ Correct Answer: C. aPTT
💡 Rationale: aPTT measures heparin effectiveness; therapeutic range is 60–80 seconds.
59. A patient’s sodium is 122 mEq/L. What symptom is most likely?
A. Bradycardia
B. Seizure
C. Dry skin
D. Constipation
✅ Correct Answer: B. Seizure
💡 Rationale: Severe hyponatremia causes cerebral edema and seizures.
60. Which lab finding is consistent with anemia?
A. RBC 6.0 million
B. Hct 60%
C. Hgb 8 g/dL
D. WBC 9,000
✅ Correct Answer: C. Hgb 8 g/dL
💡 Rationale: Hemoglobin <12 g/dL (female) or <13 g/dL (male) indicates anemia.
61. Which test evaluates liver function?
A. AST and ALT
B. Creatinine
C. CK-MB
D. Troponin
✅ Correct Answer: A. AST and ALT
💡 Rationale: Elevated AST and ALT indicate hepatocellular injury.
62. A low albumin level suggests:
A. Liver disease or malnutrition
B. Kidney infection
C. High protein intake
D. Dehydration
✅ Correct Answer: A. Liver disease or malnutrition
💡 Rationale: Albumin is made in the liver; low levels mean poor synthesis or nutrition.
63. Which result supports hypothyroidism?
A. High TSH, low T3/T4
B. Low TSH, high T3/T4
C. Normal TSH
D. High TSH and high T4
✅ Correct Answer: A. High TSH, low T3/T4
💡 Rationale: TSH rises when thyroid hormones are insufficient.
64. Which finding is most consistent with SIADH?
A. Hypernatremia
B. Hyponatremia
C. Hypokalemia
D. Hyperglycemia
✅ Correct Answer: B. Hyponatremia
💡 Rationale: SIADH causes water retention and dilutional hyponatremia.
65. Which test measures protein status in long-term malnutrition?
A. Albumin
B. Prealbumin
C. Globulin
D. Bilirubin
✅ Correct Answer: B. Prealbumin
💡 Rationale: Prealbumin has a shorter half-life and reflects acute protein status.
66. Normal fasting glucose range:
A. 50–80 mg/dL
B. 70–100 mg/dL
C. 120–150 mg/dL
D. 200–250 mg/dL
✅ Correct Answer: B. 70–100 mg/dL
67. Which electrolyte imbalance is most common in vomiting?
A. Hyperkalemia
B. Hypokalemia
C. Hypernatremia
D. Hypercalcemia
✅ Correct Answer: B. Hypokalemia
💡 Rationale: Potassium is lost through gastric fluid during vomiting.
68. Elevated D-dimer suggests:
A. Bleeding disorder
B. Clot formation (DVT/PE)
C. Anemia
D. Liver failure
✅ Correct Answer: B. Clot formation (DVT/PE)
💡 Rationale: D-dimer detects fibrin degradation in thromboembolic conditions.
69. Which lab helps assess oxygen-carrying capacity?
A. Platelets
B. Hemoglobin
C. Sodium
D. Calcium
✅ Correct Answer: B. Hemoglobin
💡 Rationale: Hemoglobin binds oxygen to red blood cells. Low values indicate anemia or blood loss.
70. Which ABG result shows respiratory acidosis?
A. pH 7.28, CO₂ 55, HCO₃ 24
B. pH 7.52, CO₂ 30, HCO₃ 22
C. pH 7.38, CO₂ 40, HCO₃ 24
D. pH 7.45, CO₂ 35, HCO₃ 25
✅ Correct Answer: A. pH 7.28, CO₂ 55, HCO₃ 24
💡 Rationale: Elevated CO₂ and low pH indicate CO₂ retention due to hypoventilation.
71. A patient’s calcium level is 11.2 mg/dL. What symptom might appear?
A. Tetany
B. Constipation
C. Muscle cramps
D. Tremors
✅ Correct Answer: B. Constipation
💡 Rationale: Hypercalcemia decreases neuromuscular excitability and slows GI motility.
72. A client with cirrhosis shows prolonged PT/INR. What does this indicate?
A. Dehydration
B. Impaired clotting
C. Vitamin C deficiency
D. Hypercalcemia
✅ Correct Answer: B. Impaired clotting
💡 Rationale: The liver produces clotting factors; dysfunction increases bleeding risk.
73. What does a high BNP value indicate?
A. Dehydration
B. Heart failure
C. Kidney stones
D. Liver disease
✅ Correct Answer: B. Heart failure
💡 Rationale: Brain Natriuretic Peptide (BNP) increases when the ventricles are stretched by fluid overload.
74. A patient’s WBC count is 2,000/mm³. What is the primary concern?
A. Risk for bleeding
B. Risk for infection
C. Fluid overload
D. Seizure activity
✅ Correct Answer: B. Risk for infection
💡 Rationale: Low WBC count (leukopenia) weakens immune defense.
75. Which lab test is used to evaluate anticoagulant therapy with warfarin?
A. aPTT
B. PT/INR
C. D-dimer
D. Fibrinogen
✅ Correct Answer: B. PT/INR
💡 Rationale: Warfarin prolongs PT and increases INR; therapeutic INR range is 2.0–3.0.
76. Normal platelet count range:
A. 50,000–100,000/mm³
B. 100,000–200,000/mm³
C. 150,000–400,000/mm³
D. 400,000–600,000/mm³
✅ Correct Answer: C. 150,000–400,000/mm³
💡 Rationale: Below 150,000 = thrombocytopenia → bleeding risk.
77. Which electrolyte imbalance may occur with loop diuretics (e.g., furosemide)?
A. Hyperkalemia
B. Hypokalemia
C. Hypernatremia
D. Hypercalcemia
✅ Correct Answer: B. Hypokalemia
💡 Rationale: Loop diuretics promote potassium loss via urine.
78. An ABG shows pH 7.32, CO₂ 30, HCO₃ 18. Interpretation?
A. Metabolic acidosis with compensation
B. Respiratory acidosis
C. Metabolic alkalosis
D. Normal ABG
✅ Correct Answer: A. Metabolic acidosis with compensation
💡 Rationale: Low HCO₃ and low CO₂ = metabolic acidosis with respiratory compensation.
79. Elevated lipase and amylase levels suggest:
A. Liver failure
B. Pancreatitis
C. Gallbladder disease
D. Hepatitis
✅ Correct Answer: B. Pancreatitis
💡 Rationale: Lipase and amylase are pancreatic enzymes that rise in inflammation.
80. A patient’s hemoglobin is 6.8 g/dL. What is the nurse’s priority?
A. Administer oxygen
B. Prepare for blood transfusion
C. Encourage ambulation
D. Monitor glucose levels
✅ Correct Answer: B. Prepare for blood transfusion
💡 Rationale: Severe anemia requires packed RBCs to restore oxygen delivery.
81. High bilirubin causes which symptom?
A. Cyanosis
B. Jaundice
C. Edema
D. Pallor
✅ Correct Answer: B. Jaundice
💡 Rationale: Bilirubin buildup causes yellow discoloration of skin and eyes.
82. Which lab confirms dehydration?
A. BUN 8 mg/dL
B. Hematocrit 60%
C. Sodium 130 mEq/L
D. Urine specific gravity 1.000
✅ Correct Answer: B. Hematocrit 60%
💡 Rationale: High hematocrit means concentrated blood due to fluid loss.
83. What does low magnesium cause?
A. Hypertension
B. Muscle weakness and tremors
C. Bradycardia
D. Constipation
✅ Correct Answer: B. Muscle weakness and tremors
💡 Rationale: Hypomagnesemia increases neuromuscular excitability.
84. Which test detects infection or inflammation?
A. CRP
B. CK-MB
C. TSH
D. Bilirubin
✅ Correct Answer: A. CRP
💡 Rationale: C-reactive protein rises with tissue inflammation.
85. Which ABG value shows respiratory alkalosis?
A. pH 7.50, CO₂ 28, HCO₃ 24
B. pH 7.30, CO₂ 50, HCO₃ 25
C. pH 7.40, CO₂ 40, HCO₃ 24
D. pH 7.38, CO₂ 60, HCO₃ 28
✅ Correct Answer: A. pH 7.50, CO₂ 28, HCO₃ 24
💡 Rationale: Hyperventilation decreases CO₂ → respiratory alkalosis.
86. Elevated BUN and creatinine together indicate:
A. Liver failure
B. Renal dysfunction
C. Heart failure
D. Lung disease
✅ Correct Answer: B. Renal dysfunction
💡 Rationale: Both are waste products cleared by kidneys.
87. Which test screens for diabetes mellitus?
A. HbA1c
B. TSH
C. Calcium
D. Sodium
✅ Correct Answer: A. HbA1c
💡 Rationale: HbA1c reflects average blood glucose over 3 months.
88. Elevated LDH is a sign of:
A. Muscle or tissue damage
B. Dehydration
C. Anemia
D. Hypothyroidism
✅ Correct Answer: A. Muscle or tissue damage
💡 Rationale: LDH is released when cells are damaged.
89. Which lab confirms infection?
A. WBC 15,000/mm³
B. Platelets 200,000
C. Hct 42%
D. Sodium 140
✅ Correct Answer: A. WBC 15,000/mm³
💡 Rationale: Elevated WBC indicates infection or inflammation.
90. Which lab should be monitored in digoxin therapy?
A. Potassium
B. Sodium
C. Calcium
D. Magnesium
✅ Correct Answer: A. Potassium
💡 Rationale: Low K⁺ increases digoxin toxicity risk.
91. Which value indicates hyponatremia?
A. 150 mEq/L
B. 135 mEq/L
C. 128 mEq/L
D. 142 mEq/L
✅ Correct Answer: C. 128 mEq/L
💡 Rationale: Normal sodium: 135–145 mEq/L.
92. Which lab finding confirms infection recovery?
A. WBC 4,500
B. WBC 18,000
C. WBC 25,000
D. WBC 3,000
✅ Correct Answer: A. WBC 4,500
💡 Rationale: Normal WBC range = 4,000–10,000/mm³.
93. Which test assesses clotting function?
A. INR
B. Troponin
C. Lipase
D. Amylase
✅ Correct Answer: A. INR
💡 Rationale: International Normalized Ratio (INR) standardizes PT for clotting assessment.
94. What does low hematocrit indicate?
A. Dehydration
B. Anemia or blood loss
C. Infection
D. Clotting disorder
✅ Correct Answer: B. Anemia or blood loss
💡 Rationale: Low Hct means fewer RBCs → reduced oxygen capacity.
95. Elevated ALT indicates damage to which organ?
A. Heart
B. Kidney
C. Liver
D. Pancreas
✅ Correct Answer: C. Liver
💡 Rationale: ALT is a specific marker for hepatocellular injury.
96. Which electrolyte imbalance is most dangerous for the heart?
A. Hyperkalemia
B. Hyponatremia
C. Hypercalcemia
D. Hypomagnesemia
✅ Correct Answer: A. Hyperkalemia
💡 Rationale: Excess potassium disrupts cardiac conduction and can cause cardiac arrest.
97. A client with COPD has ABG: pH 7.35, CO₂ 60, HCO₃ 30. Interpretation?
A. Fully compensated respiratory acidosis
B. Partially compensated acidosis
C. Respiratory alkalosis
D. Metabolic acidosis
✅ Correct Answer: A. Fully compensated respiratory acidosis
💡 Rationale: Kidneys retain bicarbonate to balance chronic CO₂ retention.
98. Which test evaluates oxygenation status?
A. ABG
B. CBC
C. INR
D. BNP
✅ Correct Answer: A. ABG
💡 Rationale: Arterial blood gases assess oxygen (PaO₂) and ventilation.
99. What lab finding supports iron deficiency anemia?
A. High ferritin
B. Low iron and ferritin
C. High hemoglobin
D. High RBC count
✅ Correct Answer: B. Low iron and ferritin
💡 Rationale: Ferritin stores iron; both drop in iron deficiency anemia.
100. Which electrolyte is primarily controlled by the parathyroid gland?
A. Sodium
B. Potassium
C. Calcium
D. Magnesium
✅ Correct Answer: C. Calcium
💡 Rationale: Parathyroid hormone regulates calcium absorption and bone release.
NCLEX Cardiac Nursing Practice
NCLEX Fundamentals of Nursing Quiz Bank
🧭 Conclusion
Understanding lab values is vital for NCLEX success and safe clinical practice. These 100 MCQs with rationales help you recognize abnormal results, anticipate complications, and take prompt action — exactly what NCLEX expects from a competent nurse.