Oedema and nephrotic syndrome — formative SAQs

SAQ 1 — Four-year-old with first presentation of oedema (10 marks, 15 minutes)

A four-year-old boy is brought to the emergency department by his parents, who describe three days of increasing puffiness around his eyes in the morning and swelling of his ankles by the evening. He had a cold the previous week. He is afebrile, his blood pressure is 95/60 mmHg, and he has periorbital and ankle oedema with a slightly distended abdomen. A random urine dipstick shows 4+ protein. His first morning urine protein-to-creatinine ratio is 320 mg/mmol, his serum albumin is 18 g/L, his creatinine is 42 micromoles per litre, and his complement C3 is normal. [1]

a) State the KDIGO 2021 diagnostic criteria for nephrotic syndrome in children, and explain why the first morning urine protein-to-creatinine ratio, rather than a random daytime dipstick, is the correct confirmation test. (3 marks) [1] [10]

b) Assuming minimal change disease, outline the initial prednisolone regimen you would prescribe, including the dose, the maximum daily dose, the point at which you convert to alternate-day dosing, and the total course duration. State the finding at four weeks that would define the steroid response. (4 marks) [1] [3]

c) Name the three life-threatening complications of nephrotic syndrome, and explain the physiological basis for the increased risk of pneumococcal peritonitis in this child. (3 marks) [11] [10]