Lipid Biochemistry USMLE Step 1 Practice Question
A 35-year-old woman on atorvastatin 40 mg daily presents with acute myalgia, proximal weakness, and dark urine. Vital signs: BP 128/82, HR 92, RR 16, Temp 37.2°C, SpO2 98%. Laboratory studies reveal creatine kinase 3500 U/L, urinalysis positive for myoglobin, and serum creatinine 1.1 mg/dL. She denies recent trauma or strenuous exercise. Which mechanism best explains her muscle injury in the context of statin therapy?
Answer choices
- AIncreased membrane fluidity from reduced cholesterol
- BDepletion of CoQ10 leading to impaired mitochondrial ATP productionCorrect answer
- CInhibition of carnitine palmitoyltransferase I
- DDirect inhibition of muscle phosphofructokinase
- EAccumulation of HMG-CoA causing lipotoxicity
- FImmune-mediated necrotizing myopathy (anti-HMGCR antibodies)
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