PRESENTATION AND DIAGNOSIS

The clinical manifestations of PIGN are variable and depend on characteristics of both host and pathogen.

Poststreptococcal disease (PSGN) classically presents as a child aged 5 to 12 who develops gross hematuria 1020 days after a bout of pharyngitis or pyoderma. It typically causes an acute nephritic syndrome, with microscopic or gross hematuria, proteinuria, and hypertension. Often, facial edema and a mild decrease in renal function are seen as well. Occasionally the proteinuria is severe enough to cause nephrotic syndrome. In less than 1% of cases, rapidly progressive glomerulonephritis occurs, leading to severe renal failure that requires dialysis. When confronted with a child who has gross hematuria following an upper respiratory infection (URI), the crucial differential is between PSGN and IgA nephropathy (IgAN), which can have similar presentations. The key to diagnosis comes from the history and lies in the latency period between pharyngitis and hematuria; for PSGN, it usually takes 10 to 14 days for the hematuria to develop (or even 3 weeks following skin infection), whereas in IgAN hematuria occurs within 5 days of URI. Patients with IgAN may also report having similar hematuric episodes in the past.