Clinically occult diffuse proliferative lupus nephritis. An age-related phenomenon.

Thirteen patients with systemic lupus erythematosus (SLE) who had normal results of urinalysis, absence of proteinuria, and normal serum creatinine values underwent renal biopsy. Three of 13 patients had diffuse proliferative glomerulonephritis (group 1). Biopsy specimens showed segmental fibrinoid necrosis, diffuse mesangial hypercellularity, and substantial immunoglobulin deposition. Group 2 comprised those patients whose histologic findings did not portend a poor prognosis. Four had mesangial proliferative glomerulonephritis, three had focal proliferative glomerulonephritis, and three had minimal mesangial widening. The values of inulin clearance in group 1 did not differ significantly from those in group 2. Patients in group 1 had a mean age of 19 years, a value significantly lower than in group 2 (41.8 years). Review of previous reports also supports the thesis that this phenomenon is age related. Our study underscores the importance of renal biopsy in patients with SLE despite the absence of clinical evidence of renal involvement, particularly in patients under 30 years of age.