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Rationales 2026 Q&A | Instant Download Pdf
1. A 62-year-old man with a history of smoking presents with
progressive dyspnea and chronic cough producing sputum.
Spirometry shows FEV1/FVC of 55%. What is the most likely
diagnosis?
A. Asthma
B. Chronic bronchitis
C. Pulmonary fibrosis
D. Pulmonary embolism
Correct answer: B. Chronic bronchitis
Rationale: An FEV1/FVC ratio <70% indicates obstructive lung
disease. In a chronic smoker with productive cough, chronic
bronchitis is most consistent with COPD phenotype characterized
by mucus hypersecretion and airway obstruction.
,2. A 24-year-old woman presents with tremor, weight loss, and heat
intolerance. Labs show low TSH and elevated free T4. What is the
most likely diagnosis?
A. Hashimoto thyroiditis
B. Graves disease
C. Subacute thyroiditis
D. Thyroid cancer
Correct answer: B. Graves disease
Rationale: Low TSH with elevated T4 indicates primary
hyperthyroidism. Graves disease is the most common cause in
young women and is mediated by TSH receptor-stimulating
antibodies.
3. A child presents with a harsh “barking” cough and inspiratory
stridor. What is the most likely causative organism?
A. Streptococcus pneumoniae
B. Haemophilus influenzae type b
C. Parainfluenza virus
D. Respiratory syncytial virus
Correct answer: C. Parainfluenza virus
Rationale: Croup is characterized by barking cough and stridor,
, most commonly caused by parainfluenza virus infection of the
upper airway.
4. Which vitamin deficiency is associated with Wernicke
encephalopathy?
A. Vitamin B1 (thiamine)
B. Vitamin B12
C. Vitamin C
D. Vitamin D
Correct answer: A. Vitamin B1 (thiamine)
Rationale: Thiamine deficiency leads to Wernicke
encephalopathy, classically presenting with ophthalmoplegia,
ataxia, and confusion, often in chronic alcohol use.
5. A patient has hematuria and RBC casts in urine. What is the most
likely diagnosis?
A. Acute tubular necrosis
B. Nephritic syndrome
C. Nephrotic syndrome
D. Urinary tract infection
Correct answer: B. Nephritic syndrome
, Rationale: RBC casts indicate glomerular inflammation,
consistent with nephritic syndrome, which presents with
hematuria, hypertension, and mild proteinuria.
6. A 45-year-old man has chest pain that improves when leaning
forward. ECG shows diffuse ST elevation. Diagnosis?
A. Myocardial infarction
B. Pericarditis
C. Aortic dissection
D. Pulmonary embolism
Correct answer: B. Pericarditis
Rationale: Diffuse ST elevation and relief with leaning forward
are classic for acute pericarditis due to inflammation of the
pericardial sac.
7. What is the most common cause of urinary tract infection in
young women?
A. Klebsiella pneumoniae
B. Escherichia coli
C. Proteus mirabilis
D. Staphylococcus saprophyticus