USMLE Step 1 / Step 2 CK / Step 3

A 58-year-old man presents 90 minutes after the onset of crushing central chest pain. ECG shows 3 mm ST elevation in leads II, III and aVF with reciprocal changes in I and aVL. The nearest centre offering primary percutaneous coronary intervention is 40 minutes away. What is the most appropriate immediate management?

• a.Transfer immediately for primary percutaneous coronary intervention
• b.Give intravenous thrombolysis in the emergency department
• c.Start a heparin infusion and arrange angiography within 72 hours
• d.Await the troponin result before deciding on reperfusion

A 19-year-old with type 1 diabetes has glucose 32 mmol/L, capillary ketones 5.8 mmol/L, pH 7.05 and potassium 3.2 mmol/L. He has received 1 L of 0.9% sodium chloride. What should happen next?

• a.Start the fixed-rate insulin infusion immediately at 0.1 units/kg/h
• b.Give intravenous sodium bicarbonate to correct the acidosis
• c.Arrange senior review and potassium replacement before or alongside insulin, with cardiac monitoring
• d.Give a subcutaneous bolus of rapid-acting insulin and review in 2 hours

A 62-year-old on empagliflozin is admitted with vomiting after a fasting-based religious observance. Glucose is 9.1 mmol/L, pH 7.24, bicarbonate 13 mmol/L and capillary ketones 4.2 mmol/L. What is the diagnosis?

• a.Hyperosmolar hyperglycaemic state
• b.Euglycaemic diabetic ketoacidosis
• c.Starvation ketosis
• d.Lactic acidosis

A 38-year-old non-smoker has progressive dyspnoea. CT shows lower-zone predominant panacinar emphysema and liver enzymes are mildly raised. What is the most likely underlying cause?

• a.Alpha-1 antitrypsin deficiency
• b.Cystic fibrosis
• c.Lymphangioleiomyomatosis
• d.Sarcoidosis

A 64-year-old man with HFrEF (ejection fraction 28%) is on ramipril, bisoprolol and furosemide with NYHA class II symptoms. eGFR is 62 and potassium 4.2 mmol/L. Which addition offers the greatest mortality benefit?

• a.Increase the furosemide dose
• b.Add digoxin
• c.Add an SGLT2 inhibitor and a mineralocorticoid receptor antagonist
• d.Add amlodipine

A 68-year-old woman on metformin 1 g twice daily has an eGFR that has fallen from 52 to 38 mL/min/1.73 m² over 6 months. She is asymptomatic with an HbA1c of 7.4%. What is the correct dose adjustment?

• a.Continue metformin 1 g twice daily and repeat eGFR in a year
• b.Reduce metformin to a maximum of 1 g/day in divided doses and monitor eGFR every 3 months
• c.Stop metformin immediately — it is contraindicated at this eGFR
• d.Increase metformin to 2.5 g/day to compensate for reduced absorption

A 4-year-old weighing 16 kg has fever and earache. What is the correct oral paracetamol dose and maximum in 24 hours?

• a.240 mg every 4-6 hours, maximum 4 doses in 24 hours
• b.500 mg every 4 hours, maximum 6 doses
• c.80 mg every 8 hours, maximum 3 doses
• d.1 g every 6 hours, maximum 4 g

An 80 kg man with a confirmed pulmonary embolism has an eGFR of 22 mL/min/1.73 m². Which enoxaparin regimen is correct?

• a.80 mg subcutaneously every 12 hours
• b.80 mg subcutaneously once daily
• c.40 mg subcutaneously once daily
• d.120 mg subcutaneously once daily

Which mechanism contributes most to the rise in PaCO2 when a hypercapnic COPD patient receives high-flow oxygen?

• a.Loss of hypoxic pulmonary vasoconstriction increasing dead-space ventilation
• b.Direct depression of the medullary respiratory centre by oxygen
• c.Increased carbon dioxide production by peripheral tissues
• d.Reduced haemoglobin affinity for carbon dioxide in the tissues

A patient with AKI has a potassium of 6.9 mmol/L with peaked T waves and a widening QRS. What is the immediate priority?

• a.Intravenous calcium gluconate, then insulin with dextrose
• b.Oral potassium binder and repeat the level in 4 hours
• c.Intravenous sodium bicarbonate as the sole treatment
• d.Urgent haemodialysis before any drug therapy

A man admitted with decompensated heart failure takes furosemide 80 mg orally each morning at home. He has gross peripheral oedema and gut congestion. What is the most appropriate initial intravenous dose?

• a.20 mg intravenously once daily
• b.40-80 mg intravenously, at least matching his oral dose, with review after each dose
• c.Continue the oral dose unchanged
• d.250 mg intravenous bolus immediately

An 82-year-old woman is confused with a respiratory rate of 24, blood pressure 104/62 mmHg, temperature 37.1°C and lactate 3.1 mmol/L after a week of dysuria. What best describes her state?

• a.Simple urinary tract infection — oral antibiotics and discharge
• b.Sepsis with hypoperfusion despite a normal temperature and blood pressure
• c.Delirium unrelated to infection
• d.Septic shock requiring immediate vasopressors

A 72-year-old woman has right-sided weakness and expressive aphasia that began 2 hours ago. CT shows no haemorrhage, blood pressure is 168/92 mmHg and glucose is 6.8 mmol/L. What is the next step?

• a.Give aspirin 300 mg and admit for observation
• b.Intravenous thrombolysis, with CT angiography to assess for thrombectomy
• c.Lower the blood pressure to below 120/80 mmHg first
• d.Wait for MRI in 24 hours before treating