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

摘要

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 per- formed 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 clin- ical diagnostic marker of LN, and in the absence of proteinuria above a certain threshold, kidney biopsies in SLE patients are often not performed. For example, the current American College of Rheumatology (ACR) guidelines suggest that a kidney biopsy be performed in patients with proteinuria >1.0 g/d, or proteinuria >0.5 g/d accompanied by hematuria or cellular casts. 3 However, there have been a handful of reports describing significant kidney pathology in SLE patients with no or minimal proteinuria, 4,5 raising the question of what constitutes an appropriate threshold for per- forming a kidney biopsy. We examined proteinuria levels at the time of kidney biopsy in our LN popula- tion to determine whether the proteinuria threshold for biopsy should be <0.5?1 g/d.