A 10-year-old boy is brought to the clinic by his parents due to swelling around his eyes and decreased urine output over the past week. He recently recovered from a sore throat two weeks ago. Past medical history is otherwise negative, and he does not take any medications. Vital signs are temperature 98.6°F (37.0°C), blood pressure 150/90 mmHg, pulse 90 beats/min, and respirations 18/min. On physical examination, he has periorbital edema and no other abnormalities. No rash is noted. Laboratory results show a blood urea nitrogen (BUN) level of 40 mg/dL and a serum creatinine level of 2.0 mg/dL. Urinalysis reveals hematuria and proteinuria.
D) Nephritic syndrome
This patient presents with edema, oliguria, hypertension, elevated BUN and creatinine, hematuria, and proteinuria following a sore throat. Nephritic syndrome is characterized by oliguria, azotemia (rising BUN/creatinine), hematuria, and hypertension. Proteinuria is variable in quantity, and nephrotic range is uncommon. The classic cause is post-streptococcal glomerulonephritis, which is suggested in this case by the recent history of a sore throat.
Answer choice A: Acute tubular necrosis, is incorrect. Acute tubular necrosis typically presents with muddy brown granular casts in the urine and a high fractional excretion of sodium (FeNa), which are not described here.
Answer choice B: IgA nephropathy, is incorrect. IgA nephropathy often presents with recurrent episodes of hematuria, typically following mucosal infections, but it does not usually present with the combination of oliguria, azotemia, and hypertension seen in nephritic syndrome.
Answer choice C: Minimal change disease, is incorrect. Minimal change disease is a common cause of nephrotic syndrome in children, characterized by massive proteinuria, hypoalbuminemia, and edema, which are not seen in this case.
Answer choice E: Nephrotic syndrome, is incorrect. Nephrotic syndrome is characterized by massive proteinuria (greater than 3.5 g/day), hypoalbuminemia, and generalized edema, which are not present in this patient.
Key Learning Point
Nephritic syndrome is characterized by oliguria, azotemia (rising BUN/creatinine), hematuria, and hypertension. Proteinuria may be seen on urinalysis though it typically is not in the nephrotic range. The classic cause is post-streptococcal glomerulonephritis.
