MRCP2-3981

A 15-year-old female presents with a two week history of worsening facial puffiness and weight gain. She has been feeling tired and lethargic for the past month since recovering from a throat infection. She had a similar infection when she was 11, but had no complications. She is not taking any medications and there are no other significant findings in her medical history. On examination, she has generalized puffiness and pitting edema in her lower limbs. Her blood pressure is 133/86 mmHg and her pulse is 88 bpm. Chest, cardiovascular, and abdominal exams are normal.

The following investigations were done:
– Hemoglobin: 146 g/L (normal range: 115-165)
– White cell count: 6 ×109/L (normal range: 4-11)
– Platelets: 250 ×109/L (normal range: 150-400)
– Serum sodium: 136 mmol/L (normal range: 137-144)
– Serum potassium: 4.0 mmol/L (normal range: 3.5-4.9)
– Serum chloride: 103 mmol/L (normal range: 95-107)
– Serum bicarbonate: 24 mmol/L (normal range: 20-28)
– Serum urea: 4.2 mmol/L (normal range: 2.5-7.5)
– Serum creatinine: 93 µmol/L (normal range: 60-110)
– Serum albumin: 25 g/L (normal range: 37-49)
– Urine dipstick: Protein +++
– 24 hour urine protein: 4.3 g/L

What is the best course of treatment for this patient?