Albuminuria in lupus nephritis: the hidden threat to cardiovascular health

Abstract Objective Systemic lupus erythematosus often leads to cardiovascular and renal complications, particularly in patients with lupus nephritis. In clinical practice, renal treatment response is commonly assessed using the Complete Renal Response criteria defined by the Consensus document of the Spanish Group for the Study of the Glomerular Diseases. These criteria, however, rely predominantly on proteinuria while albuminuria is often overlooked. The primary objective of our study was to assess the prevalence of pathological albuminuria in patients who met Complete Renal Response criteria. Secondary objectives included evaluating whether residual albuminuria identifies patients with different clinical outcomes. Methods This single-center, ambispective, observational study included 91 lupus nephritis patients. Pathological albuminuria was defined as urinary albumin-creatinine ratio > 30 mg/g. Outcomes were compared between patients with and without pathological albuminuria despite achieving Complete Renal Response. Results Among patients who met Complete Renal Response criteria, 80.5% had pathological albuminuria at the time of remission, and 55.8% continued to show it at the end of follow-up. Notably, patients with pathological albuminuria at the time of remission had significantly higher proteinuria levels both at disease onset and remission. Furthermore, persistent pathological albuminuria at follow-up was associated with more intensive antiproteinuric treatment. This therapeutic approach led to a significant reduction in both proteinuria and albuminuria titers. Conclusion Pathological albuminuria remains common in lupus nephritis patients who meet Complete Renal Response criteria. Although cardiovascular events were infrequent during follow-up, the presence of persistent pathological albuminuria in patients meeting Complete Renal Response criteria underscores the need for close monitoring and therapeutic optimization, given its well-established association with adverse renal and cardiovascular outcomes in other glomerular diseases.