The Kidney Disease: Improving Global Outcomes (KDIGO) 2025 Clinical Practice Guideline for the Management of Immunoglobulin A Nephropathy (IgAN) and Immunoglobulin A Vasculitis (IgAV) represents a focused update of Chapter 2: Immunoglobulin A Nephropathy (IgAN) / Immunoglobulin A Vasculitis (IgAV) from the KDIGO 2021 Clinical Practice Guideline for the Management of Glomerular Diseases. The aim is to assist healthcare providers caring for people with IgAN or IgAV. The update takes into consideration evidence from randomized controlled trials published through April 2023 and updated in August 2024. As in 2021, this guideline provides guidance related to diagnosis, prognosis, treatment, and special situations. Based on the new evidence, this update is mostly related to the guidance relevant to IgAN. Development of this guideline followed an explicit process of evidence review and appraisal. Treatment approaches and guideline recommendations are based on systematic reviews of relevant studies, and appraisal of the certainty of the evidence and the strength of recommendations following the “Grading of Recommendations Assessment, Development and Evaluation” (GRADE) approach. Limitations of the evidence are discussed, and areas of future research are also presented.

IgA nephropathy (IgAN) is the most common form of primary glomerulonephritis, diagnosed by the presence of dominant immunoglobulin A deposits in the mesangial matrix of the renal glomeruli. Overproduction of galactose-deficient IgA1, associated with lymphoid tissue of the intestinal mucosa, plays a central role in the disease pathogenesis. The state of the intestinal microbiota, as a major source of IgA1 production, is an important factor of shaping immune response diverse antigenic stimuli. Mucosal hyperreactivity, according to numerous studies, is crucial not only in the development but also in the progression of IgAN.

The widespread introduction of metagenomic DNA sequencing has demonstrated reduced microbial diversity of the intestinal flora in patients with IgAN compared with the healthy individuals. Another important finding is the identification of genomic loci associated with impaired permeability of the intestinal mucosa and the increased susceptibility to inflammatory diseases in IgAN patients. In addition, a relationship has been reported the genetic predisposition to IgAN, which is believed to involve multilocus interaction of risk alleles, and the composition of the microbiota.

In patients with IgAN, a direct correlation was observed between the abundance of specific bacterial families including Actinobacteriaceae, Ruminococcaceae and Bacteroidaceae, and clinical and laboratory parameters such as proteinuria, microhematuria and glomerular filtration rate. In intestinal dysbiosis, the production of key bacterial metabolites, particularly short-chain fatty acids (SCFA) are reduced. These metabolites regulate intestinal barrier permeability, immune response intensity, and antioxidant activity among other processes that may influence the course of the IgAN.

Comprehensive analysis of the intestinal microbiome, including quantitative assessment of specific bacterial species and their metabolites, represents a promising direction for further research and may facilitate the development personalized therapeutic strategies for patients with IgAN.

Sarcopenia is a syndrome characterized by the progressive and generalized loss of skeletal muscle mass, strength, and physical performance, leading to an increased risk of adverse outcomes, particularly in elderly individuals, including impaired quality of life, disability, and mortality. Chronic kidney disease (CKD) is a condition associated with accelerated aging that contributes to disturbances in nutritional and functional status, thereby predisposing patients, especially whose with end-stage kidney disease, to an increased risk of sarcopenia.

Sarcopenia is considered one of the major geriatric syndromes, while CKD is recognized as an important risk factor for the development of metabolic disturbances and chronic systemic inflammation. The main pathogenetic mechanisms of sarcopenia include mitochondrial dysfunction, age-related degeneration of motor neuron end plates, excessive apoptosis, decreased nitric oxide production, androgen deficiency, reduced activity of satellite and stem cells, systemic inflammation, and glucocorticoid exposure.

CKD is accompanied by multiple metabolic and hormonal abnormalities, including metabolic acidosis, uremia, hyperparathyroidism, and disturbances in increased insulin-like growth factor (IGF) signaling, all of which negatively affect muscle metabolism and increase the risk of sarcopenia. Intestinal dysbiosis is also considered as a potential mechanism contributing to CKD progression, and may indirectly influence muscle.

Several studies have demonstrated an association between loss of muscle mass and deterioration of kidney function, including in patients with sarcopenic obesity. Muscle mass is an important determinant of longevity in the older adults, whereas sarcopenic obesity represent a significant risk factor for adverse health outcomes. However, the prevalence and clinical significance of sarcopenic obesity in patients with CKD remains insufficiently investigated.

Systematic reviews have shown that sarcopenia in CKD patients is associated with multiple adverse clinical outcomes, including falls, fractures, and cardiovascular events. Despite the large number of studies examining these processes, the precise molecular pathways and interactions leading to muscular atrophy remain incompletely understood. Moreover, relatively few systematic reviews and meta-analyses have summarized the prevalence of sarcopenia in CKD, and most available data are limited to dialysis patients and kidney transplant recipients.

Background. Chronic kidney disease-associated pruritus (CKD-aP) can significantly impair quality of life by negatively affecting patient psycho-emotional well-being and sleep quality, while also increasing the risk of hospitalizations and mortality. In Russia, this issue remains understudied.

Objective: to assess the prevalence of pruritus and its impact on various aspects of quality of life in a Russian cohort of patients with CKD receiving maintenance hemodialysis.

Methods. The cross-sectional study included 225 patients from two dialysis centers with who has been receiving hemodialysis for more than 3 months. The presence and severity of CKD-aP were assessed using the following validated instruments: WI-NRS, Skindex-16, Itch MOS, and the 5-D Itch Scale.

Results. CKD-aP was identified in 52% of the patients, with 16% [95% CI: 11; 21] experiencing moderate-to-very severe pruritus (WI-NRS ≥4). The most commonly affected body areas were the back (53%), head (35%), shins (32%), and thighs (25%). Patients with CKD-aP, particularly those with moderate-to-severe pruritus, demonstrated more pronounced sleep disturbances. Sleep Problem Index II (SPI-II) scores were 13.3 [Q1-Q3: 0.0; 33.3] in patients without pruritus, 20 [6.7; 33.3] in those with mild pruritus, and 33.3 [20.0; 60.0] in those with moderate-to-severe pruritus (p=0.001). Patients with moderate-to-severe pruritus also had significantly higher Skindex-16 total and subscales score compared to those with mild pruritus: total score 20.7 [8.9; 35.3] vs. 7.4 [2.8; 15.5] (p<0.001), emotional subscale 14.3 [2.4; 47.6] vs. 5.2 [0.0; 16.7] (p<0.001), and symptomatic subscale 31.3 [12.5; 50.0] vs. 12.5 [4.2; 20.8] (p<0.001). The total score on the 5-D Itch Scale was also higher in patients with CKD-aP, particularly in the moderate-to-severe group: 6.0 [5.0; 8.0] in patients without pruritus, 10.0 [8.0; 11.0] in those with mild pruritus, and 13.0 [11.0; 15.0] in those with moderate-to-severe pruritus (p<0.001). Patients with pruritus had higher creatinine levels: 804.8 (217.4) μmol/L vs. 727.8 (197.8) μmol/L in patients without pruritus, p=0.0091.

Conclusions. CKD-aP is highly prevalent in a Russian cohort of patients receiving maintenance hemodialysis. Patients with pruritus, particularly of severe pruritus, experience substantial impairment in overall quality of life and across multiple domains, including sleep, daily activities, and emotional well-being.

Introduction. Atypical hemolytic uremic syndrome (aHUS) is a rare form of thrombotic microangiopathy (TMA) associated with dysregulation of the complement system. aHUS take an important place in the spectrum of kidney disease because of the high risk of kidney loss and damage to other vital organs.

Objective. The evaluate the outcomes of follow-up and treatment of patients with aHUS receiving complement-blocking therapy (CBT), with assessment of overall and renal survival.

Materials and methods. Medical records and outpatient charts of 25 patients with aHUS followed at the nephrology department of Yekaterinburg Regional Clinical Hospital No. 1 between 2014 and 2024 (10 years) were analyzed. Differential diagnostic methods, as well as morphological (kidney biopsy) and genetic studies (genetic testing of the complement system) studies, were performed. Treatment included plasma therapy (fresh frozen plasma (FFP) transfusions and/or plasma exchange) and/or CBT with eculizumab.

Statistical analysis was performed using SPSS version 24. Descriptive statistics, Kaplan-Meier survival estimates with corresponding graphs, and Fisher's exact test for intergroup comparisons were used.

Results. The identified triggers of aHUS included pregnancy and childbirth (32%), infections (16%), IgA nephropathy (8%), oral contraceptive use (8%), paint inhalation poisoning (4%), and kidney transplantation (4%). Genetic testing of the complement system was performed in 22 patients, and pathogenic variants associated with aHUS were identified in 12 (54.5%) of the examined patients. Overall patient survival rates were 96% at as: 1 year, and 89% at both 5 and 10 years. Renal survival was 100% at 1 year and 84% at 5years. Plasma therapy with FFP transfusions was administrated to 10 (40%) patients, and plasma exchange was performed in 16 (64%) patients. Specific CBT with eculizumab was used in 22 (88%) patients. Discontinuation of eculizumab was associated with a high risk of TMA recurrence (36%).

Conclusion. Long-term follow-up of 25 patients with aHUS receiving specific CBT demonstrated satisfactory overall patient survival (96% at 1 year, 89% at 5 years) and renal survival (100% at 1year, and 84% 5 years).

Introduction. Growing evidence highlights the critical role of the gut microbiota in human health, homeostasis, and disease development and progression. The gut-kidney axis plays a pivotal role in mediating the interaction between the gut microbiota and renal function. Dysbiosis and progressive biochemical alterations within the intestinal milieu contribute to chronic inflammation and increased intestinal permeability. The systemic translocation of toxic microbial metabolites, particularly uremic toxins, may result in damage to multiple organ systems, including the kidneys.

Currently, data on the gut microbiota and its metabolites in patients undergoing hemodialysis, as well as on the effects of symbiotic therapy in this population, remains limited and often conflicting.

Methods. The prospective cohort study included 26 patients receiving standard, adequate hemodialysis three times weekly. Gut microbiota samples were collected and analysed at two time points: before initiation of symbiotic therapy, and after months of treatment. Microbial composition was assessed using 16S rRNA sequencing followed by bioinformatic analysis.

Results. Synbiotics therapy significantly affected the alpha and beta diversity of the gut microbiota in patients undergoing hemodialysis. Significant changes in alpha-diversity indices were observed following treatment, with decreases in both the Shannon and Chao1 indices. Analysis of beta diversity demonstrated a significant shift in microbial community composition after completion of symbiotic therapy. Specifically, the Bray-Curtis dissimilarity index revealed significant clustering of post-treatment samples. Although baseline microbiota profiles were relatively similar among patients, microbial community dispersion increased substantially following the intervention. Synbiotic therapy was associated with relative abundances of the families Lactobacillaceae and Veillonellaceae, whereas abundancies of the families Anaerovoracaceae and Acidaminococcaceae decreased. These changes were accompanied by reduction in the relative abundance of [Ruminococcus] gnavus, [Ruminococcus] gauvreauii, Phascolarctobacterium, and Sutterella.

Conclusion. The observed changes in the gut microbiota composition following symbiotic therapy are complex and difficult to interpret definitely. Nevertheless, we believe that synbiotics administration may promote favorable alternations in the interstinal microbial community. A comprehensive assessment of the clinical significance of these changes should incorporate analyses of circulating metabolites and patient outcomes. Further studies are needed to clarify the effects of synbiotics on the gut microbiota and their potential therapeutic implications in patients undergoing hemodialysis.

Aim: To describe three cases of kidney involvement in patients with Sjögren's disease (SjD) who underwent kidney biopsy.

Methods: Medical records from three patients with SjD were analyzed. The diagnosis of SjD was established according to the 2016 ACR/EULAR criteria.

Results: The first patient (33 years old) with primary SjD presented with distal renal tubular acidosis (urine pH 8.0, urine SG 1.007; blood pH 7.27, blood HCO3- – 15.1 mmol/L, potassium 3.0 mmol/L, chloride 116 mmol/L), elevated serum creatinine level (127 µmol/L; eGFR by CKD-EPI 46 mL/min/1.73 m²) and nephrolithiasis (carbonate apatite and struvite). Kidney biopsy revealed focal glomerulosclerosis, minimal interstitial changes, and renal calcinosis. In the absence of immunological activity of SjD, no indications for escalating immunosuppressive therapy was identified.

The second patient (40 years old) had SjD associated with rheumatoid arthritis. Laboratory findings included serum creatinine 152 µmol/L (eGFR by CKD-EPI 38 mL/min/1.73 m²), proteinuria (0.69 g/24h), leukocyturia (25 cells/HPF), urine pH 7.0, and metabolic acidosis (blood pH 7.24, HCO3- 16.1 mmol/L) consistent with distal renal tubular acidosis. Kidney biopsy confirmed chronic tubulointerstitial nephritis with medullary calcinosis and no evidence of glomerular injury. Given active systemic disease, escalation of immunosuppressive therapy was initiated.

The third patient (69 years old) with an overlap syndrome (systemic sclerosis, primary biliary cholangitis, and SjD), presented an elevated serum creatinine up to 207 µmol/L (eGFR by CKD-EPI 20 mL/min/1.73 m²), minimal urinalysis abnormalities (proteinuria 0.33 g/L, leukocyturia 5-7 cells/HPF, urine pH 5.0, SG 1.020). Serum creatinine subsequently increased to 335 µmol/L, consistent with acute kidney injury. Kidney biopsy showed acute tubular injury without inflammatory changes, excluding SjD-related renal involvement and preventing unnecessary immunosuppressive therapy.

Conclusion. The cases illustrate the heterogeneity of kidney involvement in SjD. Kidney biopsy is essential for defining the type of renal lesion and guiding appropriate therapeutic decisions.

The annual increase in the number of kidney allotransplantations is associated with a delayed rise in the population of patients with nonfunctioning renal allografts. Approximately 10% of patients initiating maintenance hemodialysis have a nonfunctioning kidney transplant and continue to receive immunosuppressive therapy. As a result, a stable cohort of patients with an increased risk of infectious and hemodialysis-associated complications is being formed. Although multidisciplinary approaches to the management of patients after graft failure are actively discussed, universally accepted consensus guidelines are currently lacking.

Graft Intolerance Syndrome (GIS) is a clinical manifestation of chronic rejection activation that develops in approximately 30-40% of patients following rapid reduction or withdrawal of immunosuppressive therapy. GIS represents the most common indication for transplantectomy in patients with late allograft dysfunction, with more than one-third of nonfunctioning grafts being removed due to the development of this syndrome.

This review summarizes current literature data regarding the pathogenesis, clinical manifestations, laboratory findings, and histopathological features of GIS. Risk factors for syndrome development, clinical presentation, and the role of instrumental diagnostic methods are discussed. Particular attention is paid to the histopathological characteristics of explanted grafts, which are marked by a pronounced vascular component in combination with features of both acute and chronic rejection. Special emphasis is placed on ultrasonographic findings in renal allografts with GIS, including preserved active perfusion with disturbed angioarchitecture, Doppler patterns of collateral and stenotic blood flow, visualization of perforating vessels, the presence of perirenal collateral vascular networks, and various GIS-associated occlusive and stenotic lesions of major vessels.

Current conservative and surgical treatment strategies for patients with nonfunctioning renal allografts are also reviewed. The importance of comprehensive Doppler ultrasonography assessment for optimizing surgical management and implementing a personalized approach to patients with GIS and nonfunctioning kidney transplants in general is emphasized.