23rd June 2023

A 37-year-old known epileptic man is admitted to hospital in prolonged status epilepticus; it is successfully treated with intravenous benzodiazepines and levetiracetam.

A 37-year-old known epileptic man is admitted to hospital in prolonged status epilepticus; it is successfully treated with intravenous benzodiazepines and levetiracetam. His bloods during admission show newly impaired renal function with a serum creatinine of 290μmol/L (normal range 60-100μmol/L) and his urine dip shows 3+ blood.

Which SINGLE investigation from the list below is most likely to reveal the underlying cause of the renal impairment?