Background: Monoclonal serum free light chains (sFLC) are a well-known cause of renal impairment (RI) in patients with multiple myeloma (MM). As an indicator of monoclonality, sFLC ratio has acquired a key role in the diagnosis and monitorization of the disease. However, its interpretation is altered in patients with chronic kidney disease (CKD). This study aims to evaluate the modification of the sFLC ratio reference range in patients with CKD, and propose an optimal range for patients with CKD. Methods: Serum FLC κ/λ ratio and estimated glomerular filtration rate (eGFR) were retrospectively analyzed in 113 control patients (without hematologic disease), 63 patients with MM in complete remission and 347 patients with active MM. The three groups included patients with CKD (eGFR < 90). Results: In the group of patients without active MM (n = 176), the sFLC ratio increased at different stages of CKD without pathological significance, with an increase in the number of false positives specially when eGFR is ≤55 ml/min. An optimal range was established for patients with eGFR ≤55 ml/min/1.73 m2: 0.82–3,6 with maximum sensitivity + specificity for that group with an improvement in the Area under the curve (AUC), 0.91 (0.84–0.97) compared with the current ranges proposed by Katzmann and Hutchinson. Conclusions: This study confirms the influence of eGFR on the interpretation of the sFLC ratio, showing a decreasing specificity in progressive CKD stages when using the reference sFLC range (Katzmann), especially in patients with eFGR ≤55. According to our results, we suggest a modified optimal range (0.82–3,6) for eGFR ≤55 ml/min/1.73 m2. It is necessary to validate this modified range in larger and prospective studies.

The global overload that health systems are undergoing since the start of the COVID‐19 pandemic has forced hospitals to explore sustainable alternatives to treat vulnerable patients that require closer monitoring and higher use of resources, such as Kidney Transplant Recipients (KTRs)^1,2.The use of telemedicine and hospital‐like infrastructures represent a valid option for most patients with mild‐moderate COVID‐19, as well as for patients in the recovery phase who cannot be discharged from hospital.

The document provides a comprehensive overview of the diagnosis, monitoring, and treatment of anti-neutrophil cytoplasmic antibody-associated vasculitis (AAV) with renal involvement, focusing on granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA). It outlines the definitions, clinical presentation, histopathological classification, monitoring strategies, induction and maintenance treatments, as well as special considerations for relapsing, refractory, and frail patients with renal AAV. The document was prepared by the Catalan Group for the Study of Glomerular Diseases (GLOMCAT), which comprises nephrologists with extensive experience in the diagnosis and treatment of AAV patients. Several virtual and face-to-face meetings were held for coordination, section assignments, and content discussion. An exhaustive and systematic search of the literature was carried out, which included, among others, the following databases: PubMed, EMBASE, Cochrane Library, Google Scholar, and ClinicalTrials.gov, as well as the abstract books of national and international congresses. Overall, the document provides a comprehensive guide for clinicians managing patients with renal AAV, offering evidence-based recommendations for diagnosis, monitoring, and treatment across various clinical scenarios.

Background: Sparsentan has demonstrated significant antiproteinuric effects in randomized trials of IgA nephropathy (IgAN). However, real-world evidence remains scarce and is largely limited to short-term follow-up. Data on the durability of the antiproteinuric response in routine clinical practice are still lacking. Methods: This multicenter retrospective study included patients with biopsy-proven IgAN treated with sparsentan in routine clinical practice across Spanish centers. Patients were eligible if they initiated sparsentan outside a clinical trial and had at least 3 months of follow-up. The primary outcome was the proportion of patients achieving a >50% reduction in proteinuria at 3 months (responders). Secondary outcomes included changes in proteinuria and kidney function at 6 and 12 months, as well as safety. Results: A total of 41 patients were included. The median age was 42 years, with a median baseline estimated glomerular filtration rate (eGFR) of 44 ml/min/1.73 m2 and 95% receiving concomitant sodium–glucose cotransporter-2 (SGLT2) inhibitors. Median baseline proteinuria was 1163 mg/24 h. At 3 months, proteinuria decreased to 772 mg/24 h (median reduction 44.1%), with 51% of patients achieving a >50% reduction. Among patients with extended follow-up, the antiproteinuric effect was sustained at 6 months (median reduction 46.9%) and persisted at 12 months (median reduction 38.9%), despite increased variability. Notably, kidney function remained stable throughout follow-up, despite a moderately reduced baseline eGFR. No clinically relevant hyperkalemia or severe adverse events were observed. Conclusions: In this multicenter real-world Spanish cohort, sparsentan was associated with a sustained reduction in proteinuria in patients with biopsy-proven IgAN, maintained up to 12 months, along with preserved kidney function even in those with moderately reduced baseline eGFR, and a favorable safety profile. These findings support the effectiveness of sparsentan on top of contemporary standard of care and provide early evidence of sustained benefit in routine clinical practice.