1
MCCQE1 Exam MEGA Bank (350 Q&As) | Updated |
CDM & MCQ Format | Medical Council of Canada
Qualifying Examination Part I | Verified Grade A+
. A 72-year-old man with hypertension and diabetes presents with sudden onset of severe, tearing
chest pain radiating to the back. Blood pressure is 180/100 mmHg in the right arm and 150/90 mmHg
in the left arm. What is the most likely diagnosis?
A) Acute myocardial infarction
B) Aortic dissection
C) Pulmonary embolism
D) Pericarditis
E) Tension pneumothorax
Answer: B. Aortic dissection
Rationale: The classic presentation of aortic dissection is sudden, severe, "tearing" chest pain radiating
to the back, often with a pulse deficit or blood pressure differential between arms (>20 mmHg).
Hypertension is a major risk factor. Immediate imaging (CT angiography or TEE) is required. An MI
typically has crushing substernal pain without BP differential. PE has pleuritic pain and dyspnea.
Pericarditis has positional, sharp pain with a friction rub.
2. A 65-year-old woman with atrial fibrillation (not on anticoagulation) presents with acute onset of
right-sided weakness and aphasia. CT head is normal. What is the most appropriate next step in
management?
A) Aspirin 325 mg immediately
B) IV alteplase (tPA) within 4.5 hours of symptom onset
C) Warfarin with heparin bridging
D) Carotid endarterectomy
E) Clopidogrel 600 mg loading dose
Answer: B. IV alteplase (tPA) within 4.5 hours of symptom onset
Rationale: This patient has an acute ischemic stroke with a normal CT, ruling out hemorrhage. tPA is
indicated within 4.5 hours of symptom onset if no contraindications exist. Aspirin is given after 24 hours
if tPA is used. Anticoagulation is for secondary prevention but not acute management.
3. A 55-year-old man with a 40-pack-year smoking history presents with a chronic cough, weight loss,
and hemoptysis. Chest X-ray reveals a right hilar mass. What is the most appropriate next diagnostic
step?
pg. 1
,2
A) Sputum cytology
B) CT scan of the chest with contrast
C) PET scan
D) Bronchoscopy with biopsy
E) Mediastinoscopy
Answer: D. Bronchoscopy with biopsy
Rationale: The presentation and X-ray are highly suspicious for lung cancer. Bronchoscopy allows direct
visualization and tissue sampling for histological diagnosis, which is essential before staging and
treatment. CT chest is also done but biopsy provides definitive diagnosis.
4. A 30-year-old woman presents with fatigue, pallor, and paresthesias. Labs: Hb 80 g/L, MCV 110 fL,
normal ferritin, low B12. Peripheral smear shows hypersegmented neutrophils. What is the most
likely cause of her anemia?
A) Iron deficiency
B) Folate deficiency
C) Pernicious anemia
D) Thalassemia
E) Anemia of chronic disease
Answer: C. Pernicious anemia
Rationale: Macrocytic anemia (MCV >100), low B12, neurological symptoms (paresthesias), and
hypersegmented neutrophils are classic for B12 deficiency, commonly due to pernicious anemia
(autoimmune destruction of parietal cells → lack of intrinsic factor). Iron deficiency would be microcytic
with low ferritin. Folate deficiency lacks neurological symptoms.
5. A 68-year-old man with COPD presents with increased dyspnea, purulent sputum, and wheezing.
Oxygen saturation is 86% on room air. He is in respiratory distress. What is the initial management?
A) High-flow oxygen via non-rebreather mask
B) Controlled oxygen therapy to maintain SpO2 88-92%
C) Immediate intubation
D) IV furosemide
E) Oral prednisone alone
Answer: B. Controlled oxygen therapy to maintain SpO2 88-92%
Rationale: In COPD exacerbation, high-flow oxygen can suppress the hypoxic drive and lead to CO2
retention. Target SpO2 is 88-92%. Bronchodilators, systemic corticosteroids, and antibiotics if purulent
sputum are also indicated.
6. A 45-year-old woman presents with polyuria, polydipsia, and nocturia. Labs reveal serum sodium
150 mmol/L, serum osmolality 310 mOsm/kg, urine osmolality 200 mOsm/kg. After water
pg. 2
,3
deprivation, urine osmolality remains low and increases after desmopressin administration. What is
the diagnosis?
A) Primary polydipsia
B) Central diabetes insipidus
C) Nephrogenic diabetes insipidus
D) SIADH
E) Hyperglycemia-induced osmotic diuresis
Answer: B. Central diabetes insipidus
Rationale: Hypernatremia, high serum osmolality with inappropriately dilute urine, and response to
desmopressin (urine osmolality increases) indicate central DI (lack of ADH). Nephrogenic DI does not
respond to desmopressin. Primary polydipsia would have low/normal serum osmolality.
7. A 60-year-old man with cirrhosis presents with hematemesis. On exam, he has spider angiomata,
ascites, and splenomegaly. What is the most likely source of bleeding?
A) Peptic ulcer disease
B) Mallory-Weiss tear
C) Esophageal varices
D) Gastric cancer
E) Esophagitis
Answer: C. Esophageal varices
Rationale: Cirrhosis leads to portal hypertension, causing development of esophageal varices, which are
a common cause of upper GI bleeding in these patients. Management includes octreotide, endoscopic
band ligation, and antibiotics.
8. A 25-year-old woman presents with a malar rash, oral ulcers, and arthritis. Labs reveal positive
ANA, anti-dsDNA, and low complement levels. Urinalysis shows proteinuria and RBC casts. What is the
diagnosis?
A) Rheumatoid arthritis
B) Systemic lupus erythematosus (SLE) with lupus nephritis
C) Mixed connective tissue disease
D) Sjögren's syndrome
E) Scleroderma
Answer: B. Systemic lupus erythematosus (SLE) with lupus nephritis
Rationale: Malar rash, oral ulcers, arthritis, positive anti-dsDNA, low complement, and renal
involvement (proteinuria, RBC casts) fulfill SLE criteria. Renal biopsy would guide treatment.
pg. 3
, 4
9. A 50-year-old man with type 2 diabetes and hypertension has an eGFR of 25 mL/min/1.73m² and
urine albumin-to-creatinine ratio of 300 mg/g. What is the most appropriate medication to slow CKD
progression?
A) Furosemide
B) Lisinopril (ACE inhibitor)
C) Metoprolol
D) Amlodipine
E) Hydrochlorothiazide
Answer: B. Lisinopril (ACE inhibitor)
Rationale: ACE inhibitors (or ARBs) are renoprotective in diabetic nephropathy by reducing proteinuria
and slowing GFR decline, regardless of blood pressure. They are first-line in CKD with albuminuria.
10. A 70-year-old woman with osteoporosis is started on alendronate. What is essential counseling
about administration?
A) Take with a full glass of milk
B) Take at bedtime with a snack
C) Take on an empty stomach with plain water and remain upright for 30 minutes
D) Take with calcium supplement simultaneously
E) Crush the tablet for easier swallowing
Answer: C. Take on an empty stomach with plain water and remain upright for 30 minutes
Rationale: Bisphosphonates can cause severe esophageal irritation. They must be taken first thing in the
morning on an empty stomach, with a full glass of plain water (not mineral water, milk, or juice), and the
patient must remain upright for at least 30 minutes to prevent reflux and esophageal injury.
11. A 35-year-old woman presents with a painful, swollen right knee. Arthrocentesis reveals
negatively birefringent needle-shaped crystals under polarized light microscopy. What is the
diagnosis?
A) Septic arthritis
B) Gout
C) Pseudogout (CPPD)
D) Rheumatoid arthritis
E) Osteoarthritis
Answer: B. Gout
Rationale: Negatively birefringent urate crystals are pathognomonic for gout. Pseudogout shows
positively birefringent rhomboid crystals (calcium pyrophosphate). Septic arthritis would show positive
Gram stain/culture and purulent fluid.
pg. 4
MCCQE1 Exam MEGA Bank (350 Q&As) | Updated |
CDM & MCQ Format | Medical Council of Canada
Qualifying Examination Part I | Verified Grade A+
. A 72-year-old man with hypertension and diabetes presents with sudden onset of severe, tearing
chest pain radiating to the back. Blood pressure is 180/100 mmHg in the right arm and 150/90 mmHg
in the left arm. What is the most likely diagnosis?
A) Acute myocardial infarction
B) Aortic dissection
C) Pulmonary embolism
D) Pericarditis
E) Tension pneumothorax
Answer: B. Aortic dissection
Rationale: The classic presentation of aortic dissection is sudden, severe, "tearing" chest pain radiating
to the back, often with a pulse deficit or blood pressure differential between arms (>20 mmHg).
Hypertension is a major risk factor. Immediate imaging (CT angiography or TEE) is required. An MI
typically has crushing substernal pain without BP differential. PE has pleuritic pain and dyspnea.
Pericarditis has positional, sharp pain with a friction rub.
2. A 65-year-old woman with atrial fibrillation (not on anticoagulation) presents with acute onset of
right-sided weakness and aphasia. CT head is normal. What is the most appropriate next step in
management?
A) Aspirin 325 mg immediately
B) IV alteplase (tPA) within 4.5 hours of symptom onset
C) Warfarin with heparin bridging
D) Carotid endarterectomy
E) Clopidogrel 600 mg loading dose
Answer: B. IV alteplase (tPA) within 4.5 hours of symptom onset
Rationale: This patient has an acute ischemic stroke with a normal CT, ruling out hemorrhage. tPA is
indicated within 4.5 hours of symptom onset if no contraindications exist. Aspirin is given after 24 hours
if tPA is used. Anticoagulation is for secondary prevention but not acute management.
3. A 55-year-old man with a 40-pack-year smoking history presents with a chronic cough, weight loss,
and hemoptysis. Chest X-ray reveals a right hilar mass. What is the most appropriate next diagnostic
step?
pg. 1
,2
A) Sputum cytology
B) CT scan of the chest with contrast
C) PET scan
D) Bronchoscopy with biopsy
E) Mediastinoscopy
Answer: D. Bronchoscopy with biopsy
Rationale: The presentation and X-ray are highly suspicious for lung cancer. Bronchoscopy allows direct
visualization and tissue sampling for histological diagnosis, which is essential before staging and
treatment. CT chest is also done but biopsy provides definitive diagnosis.
4. A 30-year-old woman presents with fatigue, pallor, and paresthesias. Labs: Hb 80 g/L, MCV 110 fL,
normal ferritin, low B12. Peripheral smear shows hypersegmented neutrophils. What is the most
likely cause of her anemia?
A) Iron deficiency
B) Folate deficiency
C) Pernicious anemia
D) Thalassemia
E) Anemia of chronic disease
Answer: C. Pernicious anemia
Rationale: Macrocytic anemia (MCV >100), low B12, neurological symptoms (paresthesias), and
hypersegmented neutrophils are classic for B12 deficiency, commonly due to pernicious anemia
(autoimmune destruction of parietal cells → lack of intrinsic factor). Iron deficiency would be microcytic
with low ferritin. Folate deficiency lacks neurological symptoms.
5. A 68-year-old man with COPD presents with increased dyspnea, purulent sputum, and wheezing.
Oxygen saturation is 86% on room air. He is in respiratory distress. What is the initial management?
A) High-flow oxygen via non-rebreather mask
B) Controlled oxygen therapy to maintain SpO2 88-92%
C) Immediate intubation
D) IV furosemide
E) Oral prednisone alone
Answer: B. Controlled oxygen therapy to maintain SpO2 88-92%
Rationale: In COPD exacerbation, high-flow oxygen can suppress the hypoxic drive and lead to CO2
retention. Target SpO2 is 88-92%. Bronchodilators, systemic corticosteroids, and antibiotics if purulent
sputum are also indicated.
6. A 45-year-old woman presents with polyuria, polydipsia, and nocturia. Labs reveal serum sodium
150 mmol/L, serum osmolality 310 mOsm/kg, urine osmolality 200 mOsm/kg. After water
pg. 2
,3
deprivation, urine osmolality remains low and increases after desmopressin administration. What is
the diagnosis?
A) Primary polydipsia
B) Central diabetes insipidus
C) Nephrogenic diabetes insipidus
D) SIADH
E) Hyperglycemia-induced osmotic diuresis
Answer: B. Central diabetes insipidus
Rationale: Hypernatremia, high serum osmolality with inappropriately dilute urine, and response to
desmopressin (urine osmolality increases) indicate central DI (lack of ADH). Nephrogenic DI does not
respond to desmopressin. Primary polydipsia would have low/normal serum osmolality.
7. A 60-year-old man with cirrhosis presents with hematemesis. On exam, he has spider angiomata,
ascites, and splenomegaly. What is the most likely source of bleeding?
A) Peptic ulcer disease
B) Mallory-Weiss tear
C) Esophageal varices
D) Gastric cancer
E) Esophagitis
Answer: C. Esophageal varices
Rationale: Cirrhosis leads to portal hypertension, causing development of esophageal varices, which are
a common cause of upper GI bleeding in these patients. Management includes octreotide, endoscopic
band ligation, and antibiotics.
8. A 25-year-old woman presents with a malar rash, oral ulcers, and arthritis. Labs reveal positive
ANA, anti-dsDNA, and low complement levels. Urinalysis shows proteinuria and RBC casts. What is the
diagnosis?
A) Rheumatoid arthritis
B) Systemic lupus erythematosus (SLE) with lupus nephritis
C) Mixed connective tissue disease
D) Sjögren's syndrome
E) Scleroderma
Answer: B. Systemic lupus erythematosus (SLE) with lupus nephritis
Rationale: Malar rash, oral ulcers, arthritis, positive anti-dsDNA, low complement, and renal
involvement (proteinuria, RBC casts) fulfill SLE criteria. Renal biopsy would guide treatment.
pg. 3
, 4
9. A 50-year-old man with type 2 diabetes and hypertension has an eGFR of 25 mL/min/1.73m² and
urine albumin-to-creatinine ratio of 300 mg/g. What is the most appropriate medication to slow CKD
progression?
A) Furosemide
B) Lisinopril (ACE inhibitor)
C) Metoprolol
D) Amlodipine
E) Hydrochlorothiazide
Answer: B. Lisinopril (ACE inhibitor)
Rationale: ACE inhibitors (or ARBs) are renoprotective in diabetic nephropathy by reducing proteinuria
and slowing GFR decline, regardless of blood pressure. They are first-line in CKD with albuminuria.
10. A 70-year-old woman with osteoporosis is started on alendronate. What is essential counseling
about administration?
A) Take with a full glass of milk
B) Take at bedtime with a snack
C) Take on an empty stomach with plain water and remain upright for 30 minutes
D) Take with calcium supplement simultaneously
E) Crush the tablet for easier swallowing
Answer: C. Take on an empty stomach with plain water and remain upright for 30 minutes
Rationale: Bisphosphonates can cause severe esophageal irritation. They must be taken first thing in the
morning on an empty stomach, with a full glass of plain water (not mineral water, milk, or juice), and the
patient must remain upright for at least 30 minutes to prevent reflux and esophageal injury.
11. A 35-year-old woman presents with a painful, swollen right knee. Arthrocentesis reveals
negatively birefringent needle-shaped crystals under polarized light microscopy. What is the
diagnosis?
A) Septic arthritis
B) Gout
C) Pseudogout (CPPD)
D) Rheumatoid arthritis
E) Osteoarthritis
Answer: B. Gout
Rationale: Negatively birefringent urate crystals are pathognomonic for gout. Pseudogout shows
positively birefringent rhomboid crystals (calcium pyrophosphate). Septic arthritis would show positive
Gram stain/culture and purulent fluid.
pg. 4
