MSFinals-2636

MSFinals-2636

A 55-year-old woman visits her doctor complaining of fatigue and weakness. She has been experiencing difficulty getting up from chairs, lifting objects, and climbing stairs for the past 2 months. However, she has no issues with other movements like knitting or writing. Upon examination, she has bilateral hip and shoulder weakness. Blood tests reveal the following results: calcium 2.4 mmol/L (2.1-2.6), thyroid stimulating hormone (TSH) 4.5 mU/L (0.5-5.5), free thyroxine (T4) 12.4 pmol/L (9.0 – 18), creatine kinase (CK) 1752 U/L (35 – 250), and ESR 62 mm/hr (< 40). What is the most probable diagnosis?