USMLE® Board Review Exam Apps & Resources

A 16-year-old boy is brought to the office by his parents due to tremors and difficulty walking. Over the past year, his school performance has declined, and he has been moodier and more impulsive. His parents also note that he has been sleeping more than usual and has had a poor appetite for the past 2 months. Approximately 3 weeks ago, the patient developed a tremor in both hands that is most prominent when he reaches for an object or tries to write. The tremor has worsened significantly over the past week, and he has developed an unsteady, broad-based gait. Laboratory studies reveal elevated serum transaminases and 24-hour urinary copper excretion. The patient is prescribed penicillamine therapy. This medication primarily works through which of the following mechanisms?