ABPS Medical Knowledge & Clinical Practice Standards 5 — Questions and Answers
Question 1: A 45-year-old woman with HIV and a CD4 count of 150 cells/μL presents with fever, night sweats, and weight loss. Chest X-ray shows upper lobe cavitary lesions. What is the most likely diagnosis?
- Pneumocystis jirovecii pneumonia
- Pulmonary tuberculosis (Correct answer)
- Cryptococcal pneumonia
- Kaposi sarcoma
Correct answer: Pulmonary tuberculosis
Upper lobe cavitary lesions with constitutional symptoms in an immunocompromised patient are classic for pulmonary tuberculosis, which is a major opportunistic infection in HIV.
Question 2: Which of the following findings on echocardiography is most diagnostic of cardiac tamponade?
- Left ventricular hypertrophy with diastolic dysfunction
- Right ventricular diastolic collapse and inferior vena cava plethora (Correct answer)
- Mitral valve prolapse with regurgitation
- Aortic root dilation greater than 4.5 cm
Correct answer: Right ventricular diastolic collapse and inferior vena cava plethora
Cardiac tamponade on echocardiography classically shows right ventricular diastolic collapse, right atrial collapse, and IVC plethora due to elevated intrapericardial pressure.
Question 3: A 30-year-old woman presents with symmetric proximal muscle weakness, elevated CK, and a heliotrope rash. What is the most likely diagnosis?
- Polymyalgia rheumatica
- Dermatomyositis (Correct answer)
- Systemic lupus erythematosus
- Inclusion body myositis
Correct answer: Dermatomyositis
The combination of proximal muscle weakness, elevated CK, and heliotrope rash (violaceous periorbital discoloration) is pathognomonic for dermatomyositis.
Question 4: A physician suspects a drug-drug interaction when prescribing clarithromycin to a patient on simvastatin. What is the mechanism of this interaction?
- Clarithromycin induces CYP3A4, reducing simvastatin levels
- Clarithromycin inhibits CYP3A4, increasing simvastatin levels and myopathy risk (Correct answer)
- Simvastatin inhibits clarithromycin renal excretion
- Both drugs compete for P-glycoprotein transport
Correct answer: Clarithromycin inhibits CYP3A4, increasing simvastatin levels and myopathy risk
Clarithromycin is a potent CYP3A4 inhibitor that reduces simvastatin metabolism, dramatically increasing simvastatin plasma levels and risk of myopathy or rhabdomyolysis.
Question 5: A 55-year-old man with a 10-year history of GERD undergoes upper endoscopy showing columnar metaplasia of the distal esophagus confirmed on biopsy. What is this condition and its significance?
- Eosinophilic esophagitis, requiring dietary elimination therapy
- Barrett's esophagus, a precancerous condition requiring surveillance (Correct answer)
- Esophageal varices requiring band ligation
- Schatzki ring requiring dilation
Correct answer: Barrett's esophagus, a precancerous condition requiring surveillance
Barrett's esophagus is intestinal metaplasia of the esophageal mucosa caused by chronic GERD and carries increased risk of esophageal adenocarcinoma, requiring endoscopic surveillance.
Question 6: Which of the following best describes the ethical principle of non-maleficence in clinical practice?
- Respecting patient autonomy in all treatment decisions
- Avoiding actions that cause unnecessary harm to patients (Correct answer)
- Ensuring equitable distribution of healthcare resources
- Promoting the patient's best interest above all else
Correct answer: Avoiding actions that cause unnecessary harm to patients
Non-maleficence ('first, do no harm') obligates physicians to avoid causing unnecessary harm through treatments, procedures, or omissions of care.
Question 7: A patient with end-stage renal disease on hemodialysis presents with serum phosphorus of 7.8 mg/dL. In addition to dietary restriction, which class of medication is used to manage hyperphosphatemia?
- Phosphodiesterase inhibitors
- Phosphate binders taken with meals (Correct answer)
- Thiazide diuretics
- Bisphosphonates
Correct answer: Phosphate binders taken with meals
Phosphate binders (e.g., calcium carbonate, sevelamer, lanthanum carbonate) are taken with meals to bind dietary phosphorus in the GI tract and reduce absorption.
ABPS Medical Knowledge & Clinical Practice Standards 5
A 45-year-old woman with HIV and a CD4 count of 150 cells/μL presents with fever, night sweats, and weight loss.
Chest X-ray shows upper lobe cavitary lesions.
What is the most likely diagnosis?