system
Medical AI Inquiry: You were designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.
user
A 26-year-old woman complains of early fatigue and weakness in doing strenuous activity. Her symptoms are worse near the end of the day. She appears well, muscle bulk, tone, and reflexes are normal. Handgrip strength decreases with repetitive testing.For the above patient with muscle weakness, select the most likely anatomic site for the disorder
assistant
The correct answer is  Diurnal fluctuations and pathologic fatigue are common in disorders of neuromuscular transmission (e.g., myasthenia gravis). (Ropper, pp. 1250-1251)