Low-Grade Proteinuria Does Not Exclude Significant Kidney Injury in Lupus Nephritis

Kidney involvement is common in systemic lupus erythematosus (SLE) and is a major cause of morbidity and mortality.1 About 50% to 70% of adults and 37% to 82% of children with SLE develop lupus nephritis (LN).2 A kidney biopsy is generally performed to confirm a diagnosis of LN and to inform treatment in SLE patients who develop proteinuria with or without hematuria and/or impaired kidney function. Proteinuria is considered to be the key clinical diagnostic marker of LN, and in the absence of proteinuria above a certain threshold, kidney biopsies in SLE patients are often not performed.