MRCP-0200

MRCP-0200

A 60-year-old man has been admitted with dehydration following an attack of gastritis. His initial blood results revealed raised calcium and erythrocyte sedimentation rate (ESR). He has a history of hypertension, angina, chronic obstructive pulmonary disease (COPD), and diabetes. His most recent results have arrived on the ward, showing: Hb: 13.8 g/dL, WCC: 7.7 x 10^9/L, Plts: 212 x 10^9/L, Na+: 138 mmol/L, K+: 4.7 mmol/L, Ca+2: 2.4 mmol/L, Urea: 7.2 mmol/L, Creatinine: 104 mmol/L, Albumin: 38 g/L, IgG: 24 g/L (6.0-13.0), IgA: 2.1 g/L (0.8-3.0), IgM: 1.3 g/L (0.4-2.5). Trace amounts of Bence Jones protein have also been detected in the urine. CXR shows normal heart and mediastinal contours, clear lungs bilaterally, osteopenia of the bony skeleton with no lytic lesions. What is the most likely diagnosis?