MSFinals-4943

A 75-year-old woman with mild chronic heart failure and a baseline eGFR of 58 ml/min (> 90 ml/min) and normal electrolytes, reports to her doctor about breathlessness and increasing pedal oedema. She is prescribed a diuretic and her serum biochemistry is rechecked after two weeks, revealing hypokalaemia, hyponatraemia, and hypocalcaemia. What is the most probable diuretic that she was prescribed?