A 6-year-old boy is brought to the clinic by his parents due to swelling around his eyes and legs. The parents report that the swelling has been progressively worsening over the past week. He has otherwise been well with no recent illnesses. Past medical history is negative, and he does not take any medications. Vital signs are within normal limits. On physical examination, the child has periorbital edema and pitting edema in his lower extremities. Laboratory results show a normal complete blood count (CBC), blood urea nitrogen (BUN) 9 mg/dL, serum creatinine 0.6 mg/dL, serum albumin level 2.0 g/dL, and a total cholesterol level of 300 mg/dL. Urinalysis reveals proteinuria with a protein excretion of 4.0 g/day.
C) Minimal change disease
This patient presents with edema, normal renal function, hypoalbuminemia, hyperlipidemia, and nephrotic range proteinuria. Nephrotic syndrome is characterized by proteinuria >3.5 g/day, hypoalbuminemia, edema, and hyperlipidemia. In children, the most common cause is minimal change disease, in which podocytes with missing feet are seen on electron microscopy.
Answer choice A: Acute glomerulonephritis, is incorrect. Acute glomerulonephritis typically presents with hematuria, hypertension, and oliguria, not with massive proteinuria and hypoalbuminemia.
Answer choice B: IgA nephropathy, is incorrect. IgA nephropathy often presents with recurrent episodes of hematuria, typically following mucosal infections. Fewer than 10% of patients present with nephrotic syndrome.
Answer choice D: Nephritic syndrome, is incorrect. Nephritic syndrome is characterized by hematuria, oliguria, azotemia, and hypertension, not by the massive proteinuria and hypoalbuminemia seen in nephrotic syndrome.
Answer choice E: Post-streptococcal glomerulonephritis, is incorrect. Post-streptococcal glomerulonephritis (PSGN) typically presents with hematuria, hypertension, and edema following a streptococcal infection, but does not usually present with massive proteinuria and hypoalbuminemia. This patient has not had any recent illnesses to suggest PSGN.
Key Learning Point
Nephrotic syndrome is characterized by proteinuria >3.5 g/day, hypoalbuminemia, edema, and hyperlipidemia. In children, the most common cause is minimal change disease in which podocytes with missing feet are seen on electron microscopy.
