MSFinals-0261

MSFinals-0261

A 35-year-old woman presents to her Accident and Emergency with visual loss. She has known persistently uncontrolled hypertension, previously managed in the community. Blood tests are performed as follows:
Investigation Patient Normal value
Sodium (Na+) 148 mmol/l 135–145 mmol/l
Potassium (K+) 2.7 mmol/l 3.5–5.0 mmol/l
Creatinine 75 μmol/l 50–120 µmol/
Chloride (Cl–) 100 mEq/l 96–106 mEq/l
What is the next most appropriate investigation?