Asymptomatic acute poststreptococcal glomerulonephritis following upper respiratory tract infections caused by Group...

During an observation period of 1-2 years in 2 different districts in Japan, 104 patients were found to have upper respiratory infections caused by group A streptococci. Fourty-nine of these patients were followed prospectively to determine if renal involvement would occur. Twelve patients developed transient serum complement (CH50) depression and urinary abnormality, and 2 of these developed mild hypertension. The latent period was from 1-8 weeks after the streptococcal infection. Renal biopsies of the 12 patients with "asymptomatic" of "subclinical" acute poststreptococcal glomerulonephritis (APSGN) were examined by light, immunofluorescent and electron microscopy. Glomerular lesions ranged from mild proliferative changes to the classical pathology seen in APSGN. The 12 patients were followed for 10 years. Two of them developed persistent or intermittent hematuria, and renal biopsies obtained 4 years after the initial infection revealed mesangial proliferative glomerulonephritis without IgA deposits. The remaining patients showed no abnormal findings after the acute episode. These findings suggested that glomerular involvement after group A streptococcal infection is frequent and mesangial proliferative glomerulonephritis, which was found to develop in some, may rank with IgA nephropathy as a major cause of unexplained microscopic hematuria.