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]

SAQ 2 — Six-year-old with frequently-relapsing disease and abdominal pain (10 marks, 15 minutes)

A six-year-old girl with steroid-sensitive nephrotic syndrome has had four relapses in the last year. She presents now with three days of 3+ protein on her home dipstick, and today she has developed abdominal pain, fever of 38.9 degrees Celsius and diarrhoea. On examination her heart rate is 130 beats per minute, her blood pressure is 100/65 mmHg, her capillary refill is 4 seconds, and she has abdominal tenderness with shifting dullness. Her serum albumin is 15 g/L and her creatinine has risen from her baseline of 40 to 68 micromoles per litre. [11]

a) What is the most likely diagnosis for her abdominal pain and fever, and what is the immediate investigation and empirical management? Explain why she is vulnerable to this complication. (4 marks) [11]

b) Her tachycardia, prolonged capillary refill and abdominal pain indicate intravascular depletion despite her oedema. Outline the resuscitation you would give, naming the fluid, the dose and the accompanying drug, and explain why saline alone would worsen the situation. (3 marks) [7]

c) Given her frequently-relapsing course (four relapses in twelve months), name the steroid-sparing options that should now be considered, identify the first-line agent class, and state the evidence-based role and dose of rituximab if it is used. (3 marks) [1] [4]