IgA nephropathy (IgAN) is the most common primary glomerular disease worldwide and remains a major cause of chronic kidney disease (CKD) progression and kidney failure. Contemporary management has evolved from a predominantly supportive-care approach to a dual therapeutic paradigm that simultaneously addresses the immunological drivers of the disease and the consequences of chronic nephron loss.Nephroprotective options have expanded substantially. Sodium-glucose cotransporter-2 (SGLT2) inhibitors have demonstrated kidney and cardiovascular protection in broad CKD populations, with supportive evidence in IgAN. Endothelin receptor antagonism with sparsentan and atrasentan — and, more recently, non-steroidal mineralocorticoid receptor antagonism with finerenone — have also shown slowing of eGFR decline and reduction of albuminuria in IgAN.Disease-modifying therapy has progressed in parallel: targeted-release budesonide is currently the preferred option for patients with evidence of active immunological disease, with reduced-dose systemic glucocorticoids recommended where budesonide is unavailable or not reimbursed. Iptacopan, atacicept, telitacicept and sibeprenlimab represent the most immediate emerging therapeutic horizon, though regulatory approval remains pending in Europe for most of these agents.However, most pivotal trials were designed against a background of renin-angiotensin system (RAS) inhibition alone, which no longer fully reflects contemporary optimized conservative treatment. The key clinical question is therefore how to integrate these agents into a coherent, individualized, sequential treatment strategy, together with the appropriate duration of disease-modifying therapy. This narrative review proposes a phenotype-based, stepwise framework organized around three clinical scenarios: (1) isolated microscopic haematuria, which requires monitoring only; (2) stable kidney function with proteinuria and no evidence of immunological activity, managed with escalating nephroprotective therapy (RAS inhibition, SGLT2 inhibition, finerenone and sparsentan); and (3) progressive disease with markers of immunological activity, which requires disease-modifying therapies alongside the nephroprotective foundation; atypical presentations (rapidly progressive glomerulonephritis, pure nephrotic syndrome and thrombotic microangiopathy) are also briefly addressed. Particular attention is given to the positioning of emerging agents within the current regulatory and reimbursement landscape, drug acquisition costs, and the integration of cardiorenal protection into therapeutic decision-making.
Background: Chronic kidney disease (CKD) is a major public health problem, characterized by high cardiovascular morbidity and mortality with high healthcare costs. However, the actual prevalence of CKD in Spain is uncertain due to the wide variability of prevalence estimates (9%–15%) and the use of formulas based on creatinine or cystatin C, which have a random error margin of ±30%, limiting diagnostic reliability. This inaccuracy, together with the asymptomatic nature of CKD, leads to underdiagnosis of the disease and the resulting prevalence of occult kidney disease (O-CKD). Objectives: We designed the Mulagua Study, the first Spanish population-based cohort with measured Glomerular Filtration Rate (GFR). The main objective is to determine the actual prevalence of CKD using the measured mGFR based on plasma iohexol clearance using the dried blood spot (iohexol-DBS) technique. Secondary objectives include analyzing the error in estimation formulas, quantifying occult kidney disease, and evaluating the association of classic metabolic risk factors (metabolic syndrome, insulin resistance) with the disease. Methods: The study is population-based and cross-sectional in design, and will include 1,576 subjects aged ≥ 18 years from three municipalities in La Gomera, with a sample designed to reproduce the national population pyramid. In addition to mGFR, anthropometric and laboratory data will be collected, surveys of habits (diet, exercise, and socioeconomic status) will be conducted, and a serum, urine, and DNA biobank will be established, allowing prospective evaluation of CKD progression and its contributing factors in the future.
Background. Albuminuria is recognized as an early marker of kidney injury, an independent predictor of cardiovascular events, and mortality. Yet the frequency of abnormal albuminuria (AA; UACR ≥ 30 mg/g) and specifically mildly increased albuminuria (MIA; 10–29 mg/g) in Mediterranean populations is still poorly characterized.Methods. A cross-sectional, multicentre study including all urine albumin-to-creatinine ratio (UACR) and estimated glomerular filtration rate (eGFR) records from July 1, 2021, to June 30, 2023, in individuals ≥ 45 years [23,859 adults (median age 64 years; 54 % women)] within a Health Management Area was done. We used KDIGO 2024 classification, adding a new sub-category for MIA. Prevalence with 95 % confidence intervals (CI) was calculated and stratified by sex, age, diabetes, and hypertension.Findings. The overall prevalence of AA was 9.2 % (95 % CI 8.8–9.6), higher in men (10.8 %) than in women (7.9 %) and rose steadily with age: 3.9 % (45–59 y), 8.5 % (60–74 y), and 18.1 % (≥ 75 y). AA reached 18.8 % among those with diabetes and 22.7 % in diabetes plus hypertension, versus 6.8 % in only hypertensive people, and 1.5 % without both conditions. An inverse relationship with kidney function was observed (4.0 % in stage G1 versus 55.5 % in G4–G5). MIA was present in 8.7% (95% CI 8.4–9.0), showing similar distribution patterns at lower magnitudes; but a peak of 16.7 % occurred at eGFR 30–44 mL/ min/1.73 m², falling in G4–G5.Interpretation. Abnormal and mildly increased albuminuria affect nearly one in five adults aged 45 and over in Mediterranean primary care. Given its strong association with age, diabetes, hypertension, and declining kidney function, systematic UACR screening- including for MIA- must be prioritized to enable early detection and intervention.
La enfermedad injerto contra receptor crónica (EICR) se genera por una disregulación del sistema inmune, principalmente humoral, que puede dar lugar a patologías similares a enfermedades autoinmunes primarias. Presentamos el caso de una paciente diagnosticada de leucemia aguda mieloblástica y tratada con trasplante de progenitores hematopoyéticos dos años antes del ingreso en Nefrología por síndrome nefrótico. La paciente presentaba además lesiones cutáneo-mucosas crónicas compatibles con EICR crónica. Realizamos una revisión de la literatura de los casos de nefropatía membranosa asociada a EICR y una reflexión sobre las connotaciones fisiopatológicas de este caso y el posible cambio en la categorización de la gravedad en esta entidad.
Acute post-streptococcal glomerulonephritis (APSGN) is traditionally regarded as a self-limited post-infectious glomerulonephritis, especially in children. Although this remains accurate for most patients, it may obscure a clinically relevant subgroup with severe acute kidney injury, nephrotic-range proteinuria, rapidly progressive features, crescent formation, delayed complement recovery or persistent urinary abnormalities. Recent clinical, histological and biological data have refined the understanding of APSGN heterogeneity, including nephritis-associated plasmin receptor, urinary plasmin activity, alternative pathway activation and transient anti-factor B autoantibodies. However, these advances have not been fully translated into practical bedside risk stratification. This brief review proposes a two-axis clinical approach that separates acute severity, reflecting immediate physiological threat, from persistence risk, reflecting deviation from the expected trajectory of post-infectious resolution. To improve bedside applicability, the framework is translated into red flags, soft warning signals and reassessment windows. Nephrotic-range proteinuria at presentation is interpreted primarily as an acute-severity marker, whereas persistent proteinuria beyond the acute phase suggests persistence risk. No validated prognostic proteinuria cutoff is currently available for APSGN. Isolated microscopic haematuria alone should not prompt expanded investigation when proteinuria, blood pressure, eGFR and complement are improving. Low C3 at 6–8 weeks should trigger reassessment, whereas persistently low C3 beyond approximately 12 weeks, recurrent disease, C3-dominant biopsy findings with scant immunoglobulin deposition or discordant recovery should raise concern for C3G overlap or alternative pathway dysregulation. This approach is not a validated score, but aims to preserve reassurance for typical cases while delaying reassurance when recovery is discordant, delayed or incomplete.
Background and Objectives: Home dialysis has re-emerged as a key modality in the management of end-stage kidney disease (ESKD), offering improved patient autonomy, quality of life, and potential system-level sustainability. Yet, its roots extend deep into the early history of renal replacement therapy (RRT), when home-based care was the norm rather than the exception. By leveraging the lessons of the past patient empowerment, training models, and community-based care we may define a sustainable and person-centered future for kidney replacement therapy.To review historical evolution of home dialysis, assess current innovations and barriers, and propose a structured framework for its future implementation.Methods: Narrative review of literature (1960-2025) including registry data, policy reports, and studies on technological innovation and implementation.Results: Home dialysis was widely used in early renal replacement therapy but declined due to structural and policy-related factors. Current uptake remains low in many regions, particularly in Europe, despite evidence of cost-effectiveness and improved outcomes. Technological advances and telehealth have enhanced feasibility, but barriers persist.Conclusion: A four-pillar framework - education, policy alignment, technological innovation, and integrated support systems - provides a practical pathway to expand home dialysis and support sustainable, patient-centered renal care.
La urolitiasis es una de las enfermedades nefrourológicas más prevalentes a nivel mundial, con un coste económico significativo para los sistemas sanitarios. La evaluación metabólica se ha consolidado como una herramienta esencial para el manejo de los pacientes con alto riesgo de recurrencia, al permitir la identificación de alteraciones tratables. Este documento presenta las recomendaciones de un grupo multidisciplinar de expertos en urología y nefrología para el abordaje diagnóstico y terapéutico de las alteraciones metabólicas asociadas a la enfermedad litiásica. El consenso se alcanzó mediante la revisión de la literatura, con el objetivo de estandarizar la evaluación clínica y metabólica y, optimizar el tratamiento médico de las alteraciones metabólicas identificadas. El diagnóstico debe incluir una evaluación inicial completa que incluya analítica sérica y de orina de 24h, con parámetros específicos en función de la composición del cálculo. Las recomendaciones terapéuticas incluyen medidas generales como hidratación adecuada, restricción de sodio y proteínas animales, así como tratamientos farmacológicos dirigidos según la alteración metabólica identificada. La individualización de las estrategias terapéuticas permite reducir la incidencia de recurrencias, mejorar la calidad de vida de los pacientes y disminuir la necesidad de retratamientos. La implementación de estas recomendaciones permite avanzar hacia una medicina de precisión en la enfermedad litiásica, basada en el diagnóstico etiológico y un manejo personalizado.
The eye and kidney share profound embryological, structural, and physiological homology, rendering ocular biomarkers clinically relevant for the assessment and monitoring of chronic kidney disease (CKD). This review comprehensively examined the predictive utility of retinal and iris alterations in CKD progression. Retinal microvascular parameters, including the central retinal arteriolar equivalent (CRAE), central retinal vein equivalent (CRVE), arteriovenous ratio (AVR), and fractal dimension, were significantly associated with incident CKD, estimated glomerular filtration rate (eGFR) decline, and end-stage kidney disease risk. Optical coherence tomography (OCT) and OCT angiography (OCTA) reveal retinal neurodegeneration and microvascular rarefaction preceding a measurable decline in eGFR. Diabetic retinopathy severity independently predicts diabetic kidney disease progression, with proliferative retinopathy conferring a substantially elevated risk of kidney failure. Iris changes—encompassing calcification in uraemia, rubeosis iridis in advanced diabetic nephropathy, Lester's sign in Nail-Patella syndrome, and colobomas in Cat Eye Syndrome—offer diagnostically specific clues in hereditary and acquired nephropathies. Artificial intelligence-assisted retinal imaging platforms further augment non-invasive CKD risk stratification. Integrating structured ophthalmic evaluation into nephrology clinical pathways, supported by standardized protocols and prospective longitudinal data, could substantially advance the early detection, risk stratification, and monitoring of CKD.
Purpose Radiocephalic arteriovenous fistula (AVF) is the initial and most frequently created access for hemodialysis in patients with kidney failure. This study evaluated the impact of intraoperative dilatation of the cephalic vein on the short-term radiological and clinical outcomes of radiocephalic AVF in patients with kidney failure. Methods After applying the inclusion criteria, 91 patients who underwent RC-AVF surgery were included and divided into two groups: those who underwent intraoperative cephalic vein dilatation (46 patients) and those who did not (45 patients). Intraoperative venous dilatation was performed by pushing saline into the cephalic vein through a cannula and using pressure from assistant's finger proximally. Vein diameter and AVF flow rates were evaluated radiologically using Doppler ultrasonography at 6 weeks and fistula maturation by HFM criteria was assessed at 10–12 weeks postoperatively. Results The fistula maturation rate was 84.61% (77 out of 91); 93.47% (43 out of 46) in dilatation group compared to 75.55% (34 out of 45) in non-dilatation group (p=0.017). Doppler ultrasonography revealed significantly higher increase in post-operative vein diameters (p=0.0197) and AVF flow rates (p=0.0026) in the dilatation group compared to the non-dilation group. Complication rates, including infection and haematoma, were comparable between both groups. Conclusion Intraoperative cephalic vein dilatation during radiocephalic fistula surgery in kidney failure patients is associated with improved AVF maturation rates. This novel technique may help in technical feasibility of radiocephalic AVF surgery with improvement in short term AVF success for initiation of hemodialysis.
Background and hypothesis Extracorporeal circuit (ECC) clotting during hemodialysis (HD) compromises dialysis efficacy, increases workload, and jeopardizes patient safety. However, in routine clinical practice, ECC performance is influenced by the interaction of patient-related, technical, and pharmacological factors that are rarely evaluated simultaneously in large multicentre cohorts. Methods We conducted a multicentre retrospective observational study including all consecutive HD sessions performed across 15 hemodialysis units of Fundación Renal Española between January 1, 2023 and February 15, 2024. Recorded variables included anticoagulation type and dose, dialysis modality (high-flux HD or online HDF), vascular access, dialyzer surface area, session duration, and dialysis adequacy (KT). ECC clotting was assessed at the end of each session using a standardized visual grading scale. Associations were explored using unadjusted analyses, multivariable logistic regression adjusted for dialysis centre, and a patient-level generalized linear mixed model. Results A total of 186,637 HD sessions were analysed. ECC clotting was infrequent: 96.3% of sessions showed no or minimal clotting, 1.8% partial clotting, and 2.0% complete clotting. Sessions complicated by ECC clotting delivered a lower dialysis dose (mean KT 49.5±11.1 vs 52.2±10.1; p<0.001). In unadjusted analyses, higher clotting rates were observed in sessions without anticoagulation, with low-molecular-weight heparin (LMWH), during predilution HDF, with central venous catheters, larger dialyzer surface area, and short session duration (<60min). In adjusted analyses and in the patient-level mixed-effects model, absence of anticoagulation, central venous catheter use, and dialyzers with surface area >2.0m2 were independently associated with increased clotting risk. LMWH was associated with lower clotting risk in both models, whereas postdilution HDF showed a lower risk only in the patient-level mixed-effects model. Conclusion Although ECC clotting during HD was infrequent, it had a clear negative impact on dialysis delivery and was consistently associated with identifiable and potentially modifiable factors. Catheter-based access, lack of anticoagulation, and larger dialyzer surface area were the strongest determinants of clotting risk. The marked patient-level variability underscores the need for individualized anticoagulation and dialysis prescriptions to optimize circuit patency, dialysis adequacy, and patient safety in routine clinical practice.
En ensayos clínicos, los inhibidores del cotransportador sodio-glucosa tipo 2 (iSGLT2) conservaron la función renal, previnieron la insuficiencia cardiaca y disminuyeron la mortalidad en pacientes con enfermedad renal crónica no en diálisis, pero la experiencia en diálisis peritoneal (DP) es escasa. Hemos realizado una encuesta nacional sobre el uso de iSGLT2 en pacientes en DP en España con 10 preguntas sobre la práctica clínica habitual en relación con el uso de iSGLT2 y 4 destinadas a caracterizar como se estudia la función peritoneal y la función renal residual. Las 53 unidades de DP que respondieron trataban aproximadamente al 73 % de los pacientes en DP en España y 48 (90,6 %) tenían al menos un paciente en tratamiento con iSGLT2. En total 499 (21,1 %) de 2.368 pacientes en DP recibieron iSGLT2 en 2024, de los cuales 175 (35 %) lo habían iniciado después de haber comenzado la DP. El motivo más frecuente para iniciar tratamiento con iSGLT2 fue la insuficiencia cardiaca (63 %) seguido de la preservación de la función renal residual (53,7 %), el incremento de la diuresis (38,9 %), prevenir eventos cardiovasculares (31,5 %), preservar la membrana peritoneal (14,61 %) y disminuir la absorción peritoneal de glucosa (9,25 %), coexistiendo con frecuencia varios motivos. Cuatro (7,4 %) centros reportaron efectos adversos, siendo los más frecuentes las infecciones genitales micóticas, las infecciones urinarias y la depleción de volumen. Los iSGLT2 fueron suspendidos en 9 (1,8 %) pacientes. Casi todos los centros (52) estarían interesados en participar en un estudio observacional sobre la seguridad y eficacia de los iSGLT2 en DP. En conclusión, los iSGLT2 se usan con frecuencia en pacientes en DP y se dan las condiciones para un gran estudio nacional de práctica clínica habitual.
La apendicitis aguda constituye la urgencia quirúrgica abdominal más frecuente, y tradicionalmente se ha tratado mediante apendicectomía urgente. En los últimos años, el manejo no operatorio basado en antibioterapia ha emergido como una alternativa válida en escenarios seleccionados. En los pacientes en diálisis peritoneal, el diagnóstico puede resultar más complejo y la decisión terapéutica debe individualizarse debido al riesgo de complicaciones relacionadas con la cirugía y la posible pérdida de la técnica dialítica.Presentamos el caso de un varón de 74 años con enfermedad renal crónica secundaria a nefropatía diabética en programa de diálisis peritoneal continua ambulatoria, que acudió a urgencias por dolor en fosa ilíaca derecha y fiebre. Inicialmente no se identificó un foco abdominal claro en la tomografía computarizada. Posteriormente, ante la persistencia de la sospecha clínica, un nuevo estudio radiológico evidenció una apendicitis aguda perforada. El paciente se mantuvo hemodinámicamente estable y sin signos de peritonitis generalizada, por lo que se decidió tratamiento conservador con antibioterapia intravenosa, con evolución clínica favorable.Durante el ingreso se observó una disminución de la función renal residual que obligó a intensificar temporalmente la pauta de diálisis peritoneal. Sin embargo, la técnica dialítica pudo mantenerse, sin incidencias ni complicaciones. Este caso ilustra que el manejo conservador puede ser una alternativa segura y eficaz en los pacientes seleccionados en diálisis peritoneal, permitiendo resolver el cuadro infeccioso y preservar la técnica.
Background and objective: Rituximab is used to treat glomerular diseases (GD); however, the ideal dose schedule has not been yet defined. The aim of this study is to analyze the influence of rituximab exposure on clinical outcomes in GD.Materials and Methods: This is a single-center, open-label study including adults with GD treated with rituximab. Patients received 0.5–1 g on day 1 (sometimes repeated on day 14), and blood and urine samples were collected up to day 45 to measure biochemical markers, rituximab levels. Area under the curve (AUC) was calculated by linear regression. Clinical outcomes were measured at month 6 and 12.Results: A total of 35 cases (30 patients) were finally included in the study. Baseline characteristics: 63.3(17.6) years-old, 20(57.1%) men. Diagnosis: 14(40%) MG, 12(34.2%) AAV, 9(25.7%) INS. No infusion reactions occurred during the time of the study. Rituximab plasma concentration at day 28 (Cp28) >100µg/ml has the highest predictive capacity for complete response (CR) at month 6. There were more CR at month 6 in those cases with Cp28 >100µg/ml compared to Cp28 <100µg/ml (p= 0.026), the same was observed when combining CR at 6 and 12 months (p=0.038).Conclusions: Cp28 >100 µg/ml is associated with a higher likelihood of CR at 6 months. Although greater drug exposure was linked to better response, no significant correlation was found with longer-term outcomes, highlighting the need for further studies to define the optimal dosing schedule.
Las vasculitis asociadas a ANCA (VAA) pueden presentarse con serología negativa en aproximadamente el 10% de los casos, configurando una población subdiagnosticada con mayor riesgo de retraso terapéutico y peores desenlaces. Cuando el fenotipo clínico incluye compromiso visual isquémico en un paciente de edad avanzada con reactantes de fase aguda elevados, la presentación puede ser indistinguible de la arteritis de células gigantes (ACG), representando uno de los mayores desafíos diagnósticos en reumatología y nefrología. Mujer de 69 años que consultó por pérdida visual progresiva hasta amaurosis bilateral, cefalea y deterioro renal agudo severo (LRA KDIGO 3) con requerimiento de hemodiálisis. El perfil inmunológico completo, incluyendo ANCA por inmunofluorescencia indirecta, anti-MPO y anti-PR3, fue persistentemente negativo. La biopsia renal estableció el diagnóstico al evidenciar glomerulonefritis necrotizante crescéntrica pauciinmune con reacción granulomatosa periglomerular y arteritis granulomatosa necrotizante de arterias intrarrenales de mediano calibre con células gigantes multinucleadas, compatible con el espectro de la GPA seronegativa. Se inició inducción con metilprednisolona y ciclofosfamida intravenosa, con recuperación de la función renal y suspensión de hemodiálisis, pero sin recuperación de la agudeza visual. La sospecha inicial de arteritis de células gigantes no pudo confirmarse por biopsia de arteria temporal ni por imagen de grandes vasos, y fue descartada como diagnóstico final tras la reclasificación histopatológica renal. La ANCA-negatividad no excluye una vasculitis pauciinmune granulomatosa activa y potencialmente devastadora. Ante la coexistencia de fenotipo craneal isquémico y deterioro renal agudo, la biopsia renal precoz es determinante para establecer el diagnóstico e iniciar tratamiento inmunosupresor oportuno, independientemente del resultado serológico.
El crecimiento sostenido de la población con injerto funcionante en España, junto con la mejora de la supervivencia del injerto y del paciente, ha incrementado la complejidad y la carga asistencial asociadas al seguimiento postrasplante. En este contexto, la coordinación entre centros trasplantadores (CTR) y centros no trasplantadores (CnTR) constituye una estrategia fundamental para garantizar una atención eficiente, accesible y centrada en el paciente.El objetivo de este documento de consenso es establecer recomendaciones clínicas y organizativas para el seguimiento compartido del paciente trasplantado renal entre centros trasplantadores y centros no trasplantadores.El documento de consenso ha sido desarrollado por el grupo COMPARTE-TR, integrado por nefrólogos con experiencia en trasplante renal y seguimiento postrasplante de diferentes centros españoles. Las recomendaciones se fundamentan en la revisión de la evidencia científica disponible, en las guías nacionales e internacionales y en la experiencia clínica.Se proponen modelos organizativos para el seguimiento compartido entre CTR y CnTR, adaptables a las diferentes realidades asistenciales. Se establecen recomendaciones sobre criterios de derivación y retorno, propuestas organizativas, comunicación intercentros e información mínima necesaria para la transferencia asistencial. Asimismo, se define una propuesta de protocolo de seguimiento postrasplante que incluye la monitorización del riesgo inmunológico, infeccioso, cardiovascular, óseo-mineral y oncológico, así como la evaluación de la calidad de vida y la adherencia terapéutica. También se recogen estrategias de formación continuada, evaluación de resultados e investigación colaborativa.El seguimiento compartido entre CTR y CnTR constituye un modelo seguro y eficiente para la atención del paciente trasplantado renal. La implementación de protocolos consensuados y mecanismos estructurados de coordinación puede contribuir a homogeneizar la práctica clínica, mejorar la calidad asistencial y optimizar los resultados del trasplante renal.
Background: Rituximab is first-line therapy for moderate- and high-risk primary membranous nephropathy, yet approximately one-third of patients fail to achieve remission. Accelerated rituximab clearance through urinary loss drives interindividual pharmacokinetic variability; undetectable serum rituximab at month 3 independently predicts treatment failure. We hypothesised that serum rituximab measured on day 15 — immediately before the second infusion — predicts composite clinical response at month 6.Methods: In this single-centre prospective cohort study, 46 adults with moderate- or high-risk pMN initiating rituximab-based therapy (monotherapy, n=22; combination with calcineurin inhibitor and glucocorticoid, n=24) underwent serum rituximab measurement on day 15 using the IDKmonitor ELISA. The primary endpoint was the association between day-15 rituximab level and composite clinical response (complete or partial remission) at month 6.Results: Composite clinical response at month 6 was achieved in 32 patients (69.6%). Day-15 rituximab was significantly higher in responders than non-responders (113.2 ± 58 vs 48.6 ± 55 µg/mL; p=0.001). A threshold of 56 µg/mL yielded response rates of 87.1% versus 33.3% (sensitivity 84.4%, specificity 71.4%). Despite significantly lower albumin and higher proteinuria, combination therapy patients achieved day-15 rituximab levels comparable to monotherapy (94.1 ± 54.9 vs 92.9 ± 74.0 µg/mL; p=0.95).Conclusions: Day-15 serum rituximab predicts month-6 clinical response in pMN, advancing the earliest predictive pharmacokinetic timepoint described in this disease. Combination therapy with a calcineurin inhibitor and low-dose corticosteroid was associated with preserved day-15 rituximab exposure despite more severe baseline disease, suggesting that early proteinuria reduction may help maintain drug bioavailability. If confirmed in multicentre cohorts, day-15 measurement could enable timely treatment individualisation before irreversible underexposure leads to disease progression.
