Review Question - QID 214921

A 54-year-old man presents to an urgent care center complaining of weakness. He recently started playing tennis and his muscles have felt sore, but he became worried this morning when he was unable to get out of the bathtub. He denies headache, constipation, or changes in his weight. Past medical history is notable for acute coronary syndrome with percutaneous coronary intervention four months ago, after which he was started on aspirin, clopidogrel, metoprolol, lisinopril, and atorvastatin. His temperature is 98.8°F (37.1°C), blood pressure is 132/82 mmHg, pulse is 68/min, and respirations are 16/min. Physical exam is notable for 3/5 strength to hip flexion, hip extension, and shoulder abduction. The remainder of the neurological exam is normal. There are no skin rashes. His lab results are as follows:

Creatine kinase (CK): 920 U/L
Erythrocyte sedimentation rate (ESR): 15 mm/h

Which of the following is the most appropriate next step in management?