Albuminuria in Lupus Nephritis: The Hidden Threat to Cardiovascular Health

Background: Systemic lupus erythematosus can lead to complications such as lupus nephritis (LN). Current remission criteria for LN are based primarily on proteinuria reduction. However, KDIGO guidelines recognize that moderate albuminuria, even with preserved renal function, is an independent cardiovascular risk factor. Methods: We conducted a single-center, ambispective, observational study including 91 patients with biopsy-proven LN. The primary objective was to determine the prevalence of pathological albuminuria among patients who achieved complete renal response (CRR). The secondary objective was to compare clinical differences between patients with albuminuria <30 mg/g (Group 1) and >30 mg/g (Group 2) despite the CRR. Results: Among patients who achieved CRR, 80.5% presented with pathological albuminuria [median 126.17 (IQR 77.30–269.16) mg/g]. After intensifying antiproteinuric therapy, albuminuria was reduced by 24.7% at the end of follow-up [median follow-up: 78 (IQR 38.5–201) months]. The most commonly used antiproteinuric agents were ACE inhibitors/ARBs (77.9%) and MRAs (19.5%). Compared to Group 1, Group 2 had significantly higher proteinuria levels at onset (2.29 vs. 1.08 g/g; p < 0.001) and at remission (0.36 vs. 0.10 g/g; p < 0.001). Persistent pathological albuminuria was linked to more intensive antiproteinuric regimens [median number of agents: 1 (IQR 1–3) vs. 1 (IQR 0–2); p = 0.001]. This strategy resulted in a significant reduction in urinary protein-to-creatinine ratio (-0.15 g/g; p = 0.004) and albumin-to-creatinine ratio (-48.4 mg/g; p = 0.002). No differences were observed in cardiovascular events or mortality between groups. Conclusion: Pathological albuminuria persists in a substantial proportion of patients with LN despite achieving CRR. Although cardiovascular events were infrequent, our findings support the consideration of albuminuria as a modifiable prognostic marker in LN. Incorporating albuminuria into the definition of renal remission may help guide more personalized therapeutic strategies.Cohort distribution as defined by the KDIGO guidelines, among patients that achieved CRR.