11 USMLE Step 2 CK Clinical Review Questions with Answers (Set 5)

These 11 USMLE Step 2 CK clinical review questions are short clinical cases on diagnosis and next-step management, including Delirium, Helicobacter pylori, Amiodarone-induced pulmonary toxicity, Aortic stenosis, Azithromycin plus doxycycline, Malignant hyperthermia, Ménière disease, Hemolytic anemia. Each question includes the correct answer and an explanation.

Written by Dr. Ray Makar, MD, author of the Repeated USMLE Questions eBook series.

Prefer video? Watch daily USMLE case questions on MedFocus by Dr. Ray on YouTube.

How to use this page: read the question, pick your answer, then tap Show Answer and Explanation.

Questions

Question 1. A 72-year-old hospitalized patient develops acute confusion and agitation. He has a fluctuating level of consciousness and visual hallucinations. What is the most likely diagnosis?

A- Acute psychosis
B- Alzheimer disease
C- Delirium
D- Major depressive disorder

C- Delirium- Delirium presents with an acute onset, fluctuating consciousness, and impaired attention, commonly in hospitalized or elderly patients.
The correct answer is C

 

Question 2. A 45-year-old man presents with epigastric pain that improves with meals. Endoscopy shows a duodenal ulcer. Which organism is most commonly associated with this condition?

A- Campylobacter jejuni
B- Escherichia coli
C- Helicobacter pylori
D- Staphylococcus aureus

C- Helicobacter pylori- H. pylori infection is the most common cause of duodenal ulcers, which typically improve with food.
The correct answer is C

 

Question 3. A 60-year-old woman presents with progressive dyspnea and dry cough. CT scan shows bilateral ground-glass opacities. She has been on amiodarone for several years. What is the most likely diagnosis?

A- Acute respiratory distress syndrome
B- Amiodarone-induced pulmonary toxicity
C- Community-acquired pneumonia
D- Pulmonary embolism

B- Amiodarone-induced pulmonary toxicity- Amiodarone can cause chronic interstitial lung disease with ground-glass opacities and progressive dyspnea.
The correct answer is B

 

Question 4. A 59-year-old man presents with progressive exertional dyspnea and fatigue. Cardiac exam reveals a harsh systolic murmur best heard at the right upper sternal border that radiates to the carotids. What is the most likely diagnosis?

A- Aortic regurgitation
B- Aortic stenosis
C- Mitral regurgitation
D- Mitral stenosis

B- Aortic stenosis- Aortic stenosis causes a harsh crescendo–decrescendo systolic murmur radiating to the carotids and presents with dyspnea, syncope, or angina.
The correct answer is B

 

Question 5. A 26-year-old woman presents with lower abdominal pain, fever, and purulent cervical discharge. Pelvic exam reveals cervical motion tenderness. What is the most appropriate initial treatment?

A- Azithromycin alone
B- Azithromycin plus doxycycline
C- Metronidazole alone
D- Oral fluconazole

B- Azithromycin plus doxycycline- Pelvic inflammatory disease requires empiric broad-spectrum coverage for Neisseria gonorrhoeae and Chlamydia trachomatis.
The correct answer is B

 

Question 6. A 71-year-old man develops high fever, muscle rigidity, tachycardia and confusion while recovering from general anesthesia for hip surgery. Labs show a markedly elevated creatine kinase, hyperkalemia and acidosis. What is the most likely diagnosis?

A- Malignant hyperthermia
B- Neuroleptic malignant syndrome
C- Serotonin syndrome
D- Thyroid storm

A- Malignant hyperthermia- Malignant hyperthermia is a genetic (RYR1) reaction to volatile anesthetics or succinylcholine, causing uncontrolled calcium release in skeletal muscle: hyperthermia, rigidity, tachycardia, rising end-tidal CO2, high CK, hyperkalemia and acidosis. Treat by stopping the trigger and giving IV dantrolene. Neuroleptic malignant syndrome follows antipsychotics, and serotonin syndrome follows serotonergic drugs.
The correct answer is A

 

Question 7. A 33-year-old woman presents with episodic vertigo, tinnitus, and hearing loss. Symptoms last several hours and resolve spontaneously. What is the most likely diagnosis?

A- Acoustic neuroma
B- Benign paroxysmal positional vertigo
C- Ménière disease
D- Vestibular neuritis

C- Ménière disease- Ménière disease causes episodic vertigo, tinnitus, and sensorineural hearing loss due to endolymphatic hydrops.
The correct answer is C

 

Question 8. A 48-year-old man presents with dark urine, jaundice, and fatigue. Labs show elevated indirect bilirubin and increased reticulocyte count. What is the most likely diagnosis?

A- Acute viral hepatitis
B- Autoimmune hepatitis
C- Hemolytic anemia
D- Primary biliary cholangitis

C- Hemolytic anemia- Hemolytic anemia causes indirect hyperbilirubinemia, reticulocytosis, and dark urine due to increased red blood cell breakdown.
The correct answer is C

 

Question 9. A patient with chronic kidney disease develops secondary hyperparathyroidism. Which of the following biochemical changes directly stimulates parathyroid hormone (PTH) secretion in this condition?

A- Decreased 1,25-dihydroxyvitamin D levels
B- Decreased serum phosphate
C- Increased calcium-sensing receptor activation
D- Increased intestinal calcium absorption

A- Decreased 1,25-dihydroxyvitamin D levels- In CKD, impaired renal 1-alpha-hydroxylase lowers active vitamin D, reducing calcium absorption and directly stimulating PTH release.
The correct answer is A

 

Question 10. A child presents with recurrent viral infections. Flow cytometry shows absent MHC class I expression on all nucleated cells. Which immune defect best explains this finding?

A- Defective beta-2 microglobulin synthesis
B- Impaired CD4+ T-cell differentiation
C- Impaired TAP transporter function
D- Loss of thymic epithelial cells

C- Impaired TAP transporter function- TAP transports cytosolic peptides into the ER for loading onto MHC class I. Without TAP, MHC I molecules are unstable and absent on the cell surface.
The correct answer is C

 

Question 11. A patient has a mutation that prevents NADH oxidation in the mitochondrial electron transport chain. Which metabolic consequence is most likely?

A- Decreased ATP production from oxidative phosphorylation
B- Increased flux through the citric acid cycle
C- Increased mitochondrial membrane potential
D- Reduced lactate formation

A-Decreased ATP production from oxidative phosphorylation- NADH oxidation drives proton pumping and ATP generation. Impairment reduces oxidative phosphorylation and cellular ATP production.
The correct answer is A

 

High-yield points from this set

  • Delirium presents with an acute onset, fluctuating consciousness, and impaired attention, commonly in hospitalized or elderly patients.
  • induced pulmonary toxicity- Amiodarone can cause chronic interstitial lung disease with ground-glass opacities and progressive dyspnea.
  • Aortic stenosis causes a harsh crescendo–decrescendo systolic murmur radiating to the carotids and presents with dyspnea, syncope, or angina.
  • Pelvic inflammatory disease requires empiric broad-spectrum coverage for Neisseria gonorrhoeae and Chlamydia trachomatis.
  • Ménière disease causes episodic vertigo, tinnitus, and sensorineural hearing loss due to endolymphatic hydrops.

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