A 9-year-old boy is brought to the emergency department due to lethargy, headache, and nausea since this morning. In addition, the patient has had decreased urine output over the past 48 hours. He reports no abdominal or joint pain, dysuria, or shortness of breath. The patient has no chronic medical conditions; 2 weeks ago, he had a sore throat that resolved spontaneously. Temperature is 37.2 C (99 F), blood pressure is 170/102 mm Hg, pulse is 98/min, and respirations are 20/min. The oropharynx is clear. The neck is supple, and there is no lymphadenopathy. Periorbital, scrotal, and pedal edema are present. There is no rash. Complete blood count is normal. Serum creatinine is 1.9 mg/dL. Urinalysis reveals moderate blood and 2+ protein. Which of the following is the best next step in management of this patient?

Question

A 9-year-old boy is brought to the emergency department due to lethargy, headache, and nausea since this morning.  In addition, the patient has had decreased urine output over the past 48 hours.  He reports no abdominal or joint pain, dysuria, or shortness of breath.  The patient has no chronic medical conditions; 2 weeks ago, he had a sore throat that resolved spontaneously.  Temperature is 37.2 C (99 F), blood pressure is 170/102 mm Hg, pulse is 98/min, and respirations are 20/min.  The oropharynx is clear.  The neck is supple, and there is no lymphadenopathy.  Periorbital, scrotal, and pedal edema are present.  There is no rash.  Complete blood count is normal.  Serum creatinine is 1.9 mg/dL.  Urinalysis reveals moderate blood and 2+ protein.  Which of the following is the best next step in management of this patient?

Quizplus · Accepted Answer

11ec25c8_d727_0c3e_bc81_dbe5a561eabe_MD0003_00 This patient with hypertension, edema, and hematuria several weeks after group A Streptococcus infection (eg, pharyngitis) likely has acute poststreptococcal glomerulonephritis (APSGN). APSGN, a nephritic syndrome, results from immune-complex deposition between the glomerular basement membrane (GBM) and the mesangium, as well as from complement (C3) activation and leukocytic inflammation that damages glomeruli. Most cases are self-limited, with complete resolution and return to normal kidney function within weeks. However, during the acute course, a spectrum of disease from asymptomatic to acute kidney injury and fulminant nephritic syndrome can occur, depending on the amount of immune complex deposition and GBM thickening. Patients with nephritic syndrome, such as this one, have decreased glomerular filtration (eg, ↑ serum creatinine) and impaired sodium excretion (eg, hypertension). Concurrent damage to the subepithelial podocytes results in increased urinary loss of protein and red blood cells (eg, hematuria, proteinuria), causing decreased intravascular oncotic pressure and third spacing. The culmination of these effects leads to volume overload, with possible hypertension and edema requiring treatment with loop diuretics (eg, furosemide). Adjunctive treatment with additional antihypertensives may be indicated (eg, hypertensive encephalopathy, hypertension refractory to diuresis), with possible dialysis in medically refractory cases. (Choice A) Protein restriction is used in chronic kidney disease because high protein intake may increase intraglomerular pressure and cause hyperfiltration, thereby aggravating the disease. However, in APSGN, decreased glomerular filtration rate (GFR) and protein spilling lead to volume overload and edema, which protein restriction does not help. (Choice C) When additional antihypertensive therapy is required (eg, hypertensive encephalopathy, no response to diuresis), calcium channel blockers (eg, nifedipine) are the drugs of choice. ACE inhibitors (eg, lisinopril) are used with caution in acute kidney injury because of the risk of exacerbating hyperkalemia. (Choice D) In prerenal oliguria, a normal saline infusion may be indicated. However, the oliguria in APSGN is secondary to decreased GFR due to intrarenal pathology; normal saline infusion would worsen this patient's volume overload, edema, and hypertension. (Choice E) Some antibody-mediated nephritic syndromes (eg, Goodpasture) are responsive to plasmapheresis; this young patient with recent pharyngitis and acute-onset symptoms most likely has APSGN. Plasmapheresis is costly and not indicated because APSGN is self-limited. In addition, clearing antibody-antigen complexes from blood does not clear them significantly faster from mesangium. Educational objective: Acute poststreptococcal glomerulonephritis, a complication of group A Streptococcus infection (eg, pharyngitis), typically presents with hematuria, edema, and hypertension. Management is mainly supportive. Complications of volume overload (eg, hypertension, edema) require treatment with loop diuretics.

A 9-Year-Old Boy Is Brought to the Emergency Department Due