A 59-year-old man comes to the physician for a 6-month history of worsening pain and stiffness of his buttocks and thighs. He has lost 8 pounds during this time. He takes no medications and does not smoke cigarettes. Blood pressure is 130/85. His younger brother has rheumatoid arthritis. Physical examination shows 5/5 strength in the upper and lower extremities. Serum creatine kinase is elevated. The thyroid gland is not enlarged. Serum TSH is 4.5 mIU/L (NR 0.5-5.0). Which of the following is the most likely diagnosis?
Fibromyalgia
Hashimoto disease
Intermittent claudication
Polymyalgia rheumatica
Polymyositis
