Proteinuria in the nonnephrotic range and/or hematuria unaccompanied by edema, reduced GFR, or hypertension can be due to multiple causes (Table 145-5 Glomerular Causes of Asymptomatic Urinary Abnormalities).
Thin Basement Membrane Nephropathy 
Also known as benign familial hematuria, may cause up to 25% of isolated, sustained hematuria without proteinuria. Diffuse thinning of the glomerular basement membrane on renal biopsy, with minimal other changes. May be hereditary, caused in some instances by defects in type IV collagen. Pts have persistent glomerular hematuria, with minimal proteinuria. The renal prognosis is controversial but appears to be relatively benign.
Another very common cause of recurrent hematuria is of glomerular origin. Episodes of macroscopic hematuria are present with flulike symptoms, without skin rash, abdominal pain, or arthritis. Renal biopsy shows diffuse mesangial deposition of IgA, often with lesser amounts of IgG, nearly always by C3 and properdin but not by C1q or C4. Prognosis is variable; 50% develop ESRD within 25 years; men with hypertension and heavy proteinuria are at highest risk. Glucocorticoids and other immunosuppressive agents have not proved successful, except in pts who present with rapidly progressive GN and/or proliferative GN on renal biopsy. Rarely causes loss of allografts.
Glomerulopathies Associated with Multisystem Disease
(See Table 145-6 Serologic Findings in Selected Multisystem Diseases Causing Glomerular Disease.)