Glomerular lesions in asymptomatic microscopic hematuria discovered on routine medical examination

Renal biopsies from 145 patients with asymptomatic microscopic hematuria were studied with light microscopic, electron microscopic and immunofluorescence antibody techniques. The predominant lesions were a diffuse proliferative glomerulonephritis (mesangial hypercellularity) with focal epithelial crescents and focal segment and/or global sclerosis in many of them; and a minimal lesion with increased mesangial matrix and mild mesangial hypercellularity. Focal and segmental glomerulonephritis, diffuse mesangio-capillary and membranous glomerulonephritis were less common lesions. IgA deposition with other immunoglobulins was seen in over 50% of cases, with an IgA IgG-Beta1C-globulin combination being the common lesion. IgA secretory piece and HBs antigen were not found in the glomeruli and early complement components C1q and C4 were absent. Changes in the mesangium, basement membranes of capillary loops and mesangial osmophilic deposits reflect the pathogenesis of this disease. In addition to the above 145 patients, thirty-five cases of persistent microscopic hematuria classified as symptomatic, with a past history of "acute nephritis", lumbar pain and other complaints; and 11 patients with macroscopic hematuria, painless or associated with "acute nephritis" had similar glomerular lesions. Raised ASOT levels suggest the role of an upper respiratory infection in the exacervation or precipitation of this lesion. The IgA depositon may be associated with deposition of other antibodies in a picture of chronic glomerulonephritis, post-streptococcal or otherwise. 6 of the 145 patients with asymptomatic microscopic hematuria have gone into chronic renal failure in 3.5 years.