Commentary on the Current Guidelines for the Diagnosis of Lupus Nephritis Flare.

Lupus nephritis flare is a frequent complication in patients with systemic lupus erythematosus. Recognizing disease activity is crucial in lupus nephritis management. Proteinuria magnitude and urine sediment change are major clinical indicators of lupus nephritis activity. This work updates these insights in light of recent findings regarding proteinuria quantification and urine sediment analyses. Currently, BILAG and SLEDAI estimate proteinuria magnitude based on the protein/creatinine ratio of "spot" (single void collections) or "intended" 24-h urine collections without specifying the extent to which the collection approaches a 24-h collection. As discussed here, and based on our recently published work, these approaches often incur serious errors that can adversely affect SLE patient management. Also incorporated into this work is a new analysis of the clinical significance of urine sediment hematuria and pyuria changes with regard to recent-onset SLE glomerulonephritis (GN) flare. This analysis is based on a prospective study of urine sediment changes in the Ohio SLE Study, which was an NIH-sponsored prospective observational study of SLE GN patients with SLE flare of recent onset. We propose that BILAG and SLEDAI renal flare criteria can be made more rigorous by incorporating recently published insights into proteinuria quantification using the protein/creatinine ratio of an intended 24-h urine collection that is at least 50% complete based on its creatinine content. Also proposed are new insights into the interpretation of urine sediment hematuria and pyuria based on findings from the Ohio SLE Study.