Review Question - QID 105565

This patient has facial swelling and hypertension and recent impetigo, consistent with post-streptococcal glomerulonephritis (PSGN). For patients with suspected nephritic or nephrotic syndromes, urinalysis is the most appropriate first step in management.

PSGN is a nephritic syndrome often seen in children with recent history of group A streptococcal infection. While not fully understood, the pathophysiology of this condition is thought to involve glomerular immune complex deposition and complement system activation leading to glomerular dysfunction. Patients often report a history of sore throat or skin infection, and it may occur in patients who were treated appropriately. Patients typically present 2-6 weeks after the inciting infection, though some patients will report no history of associated streptococcal infection or infectious symptoms. Patients often report a history of fatigue, facial or generalized swelling, and dark urine. Swelling arises due to a combination of salt and water retention as a result of renal dysfunction as well as urinary protein loss. The first step in evaluation of patients with suspected PSGN is to obtain a urinalysis. Urinalysis will typically demonstrate hematuria (with or without RBC casts) and urinary protein. Management is generally focused on supportive care, and most patients recover fully without complications.

Rahman et al. discuss acute kidney injury (AKI), which is characterized by an abrupt deterioration in kidney function. The best surrogate marker of renal function is an increase in serum creatinine level. AKI may or may not result in reduced urine output. Initial tests should include serum creatinine level, complete blood count, urinalysis, and fractional excretion of sodium.

Figure A demonstrates a child with periorbital edema.

Incorrect Answers:
Answer 1: While Antistreptolysin O titers would likely be positive in this patient with PSGN, it is used to confirm the diagnosis, and is not the most appropriate first diagnostic step.

Answer 2: CT scan of the abdomen and pelvis with contrast would be appropriate if a renal mass or renal trauma were suspected. However, it is not indicated in diagnosis of suggested post-streptococcal glomerulonephritis.

Answer 3: Empiric antibiotic therapy may be indicated for patients with PSGN who present with evidence of current streptococcal infection. However, it would not be indicated in this patient without symptoms attributed to ongoing streptococcal infection.

Answer 4: Renal ultrasound may be appropriate if a renal mass or renal trauma were suspected. It can also assess for blood flow to the kidney in conditions such as as renal artery stenosis.

Bullet Summary:
For patients with suspected nephritic or nephrotic syndromes, urinalysis is the most appropriate first step in management.