MRCP2-3870

A 21-year-old woman of African descent presents to your Nephrology Clinic with a complaint of dipstick-positive proteinuria and lower limb edema. She has no significant medical history and is not taking any regular medication. She reports occasional joint pain in her elbows and knees, which she manages with paracetamol. On examination, her blood pressure is 118/60 mmHg.

What is the most suitable test to determine the underlying diagnosis of this patient?