MRCP2-4680

A 70-year-old woman presents to the emergency department due to difficulty coping at home. She has been experiencing weakness and fatigue for the past month, and has been having trouble getting out of bed. Her arms feel heavy in the morning, and she has been experiencing shoulder pain and reduced appetite. She has a medical history of stroke, atrial fibrillation, heart attack with coronary stenting, and hypertension. Her vital signs are normal except for a temperature of 37.7 degrees. Her joints are not tender or swollen, and her visual acuity is normal. Blood tests reveal a hemoglobin level of 122 g/l, platelet count of 366 * 109/l, white blood cell count of 8.9 * 109/l, sodium level of 137 mmol/l, potassium level of 4.1 mmol/l, urea level of 6.2 mmol/l, and creatinine level of 122 µmol/l. What is the most likely diagnosis?