Natural History and Renal Pathology in Patients with Isolated Microscopic Hematuria

Background/Aims: No definite conclusions have been reached about the natural history of patients with isolated microscopic hematuria (IMH). In this study, we observed the natural history of patients with IMH and examined factors related to a pathologic diagnosis and subsequent prognosis. Methods: We retrospectively evaluated 156 subjects with IMH who had a renal biopsy performed. Of the 156 subjects, 33.3% were diagnosed with IgA nephropathy, 23.7% with mesangial proliferative glomerulonephritis, 15.4% with glomerular minor lesion, and 12.8% with thin basement membrane nephropathy; 6.4% had normal biopsies. Results: We followed up with 100 subjects for about 31 months. During this follow-up period, two subjects who had received a pathologic diagnosis of IgA nephropathy developed chronic kidney disease. During the course of the study, one of these subjects presented with proteinuria and hypertension and the other with proteinuria. The overall incidences of proteinuria and hypertension were 6% and 5% respectively. Conclusions: The prognosis for patients with IMH was relatively favorable, but patients developing proteinuria and/or hypertension require careful observation and management during the follow-up period. (Korean J Intern Med 2009;24:356-361)