Historically, it takes an average of 17 years to move new treatments from clinical evidence to daily practice. Given the highly effective treatments now available to prevent or delay kidney disease onset and progression, this is far too long. The time is now to narrow the gap between what we know and what we do. Clear guidelines exist for the prevention and management of common risk factors for kidney disease, such as hypertension and diabetes, but only a fraction of people with these conditions worldwide are diagnosed, and even fewer are treated to target. Similarly, the vast majority of people living with kidney disease are unaware of their condition, because in the early stages it is often silent. Even among patients who have been diagnosed, many do not receive appropriate treatment for kidney disease. Considering the serious consequences of kidney disease progression, kidney failure, or death, it is imperative that treatments are initiated early and appropriately. Opportunities to diagnose and treat kidney disease early must be maximized beginning at the primary care level. Many systematic barriers exist, ranging from patient to clinician to health systems to societal factors. To preserve and improve kidney health for everyone everywhere, each of these barriers must be acknowledged so that sustainable solutions are developed and implemented without further delay.

Secondary hyperparathyroidism is a common and serious complication of chronic kidney disease (CKD) in both dialysis and predialysis patients. Progression of chronic kidney disease with a loss of active nephrons and interstitial fibrosis lead to a cascade of complications, including vitamin D deficiency, hyperphosphatemia, decreased calcium absorption, and increased production of parathyroid hormone. Advance development of drug therapy, targeting various components of hyperparathyroidism (HPT) pathogenesis, and in particular, the advent of calcimimetics, significantly reduced the number of patients with uncontrolled HPT. However, a substantial proportion of patients are drug-resistant, and therefore need surgical correction of HPT. Parathyroidectomy has been widely reported to improve bone mineral density, reduce the risk of fractures, and improve the quality of life and survival of dialysis patients. The review is devoted to the most pressing and controversial issues of surgical treatment of secondary HPT. The topics addressed in the review are as follows: 1) indications for surgical correction are presented according to various clinical National guidelines; 2) issues of preoperative topical localization of the parathyroid glands and its influence on the surgery outcomes; 3) comparative analysis of the sensitivity and specificity of various imaging technics (ultrasound, scintigraphy, computed tomography) alone or in combination; 4) controversial issues of choosing the most optimal extent of surgery. Current available literature does not provide consensus about optimal for this highly comorbid group of patients. This review provides information on modern surgical treatment options, their advantages and disadvantages. As a rule, subtotal parathyroidectomy is associated with a higher risk of disease relapse, while severe hypocalcemia more often observed after a total parathyroidectomy. The choice of the extent of surgical intervention is considered in view of the HPT recurrence rate, predicted life expectancy, and perspective of kidney transplantation. Possible postoperative complications are described. Thus, the problems of examining and treating patients with CKD stage 5 and secondary HPT remain relevant.

Introduction: immunoglobulin A (IgA) nephropathy is the most common primary chronic glomerulonephritis worldwide and in Russia. IgA nephropathy is one of the most significant causes of the development of end-stage chronic kidney disease, which requires renal replacement therapy. The disease occurs in people of predominantly young and working age (from 20 to 40 years), which determines its social significance. A high rate of relapse of IgA nephropathy after donor kidney transplantation was reported. The spectrum of clinical manifestations and morphological picture of the disease is diverse, ranging from isolated urinary syndrome (asymptomatic microhematuria/proteinuria) to nephritic activity, nephrotic syndrome, and even rapidly progressive glomerulonephritis. The review aimed to present current view on the pathogenesis of IgA nephropathy Main information: at present, a fundamental understanding of the nature of this disease has been formed, and some data have appeared on the more subtle mechanisms of its development. It has become obvious that IgA nephropathy is an autoimmune disease based on the immune complexes (IC) formation. Galactose-deficient IgA1 (Gd-IgA1) acts as an autoantigen and is formed as a result of underglycosylation in the hinge region of this immunoglobulin heavy chains. Its production is carried out by cells of the mucosa-associated lymphoid tissue, namely nasal-associated lymphoid tissue (NALT) and gut-associated lymphoid tissue (GALT). However, in recent years, the so-called “gut-kidney” axis has played a significant role in the pathogenesis of IgA nephropathy. IC, binding to special receptors located on the mesangiocytes of the renal glomerulus, trigger the process of its damage. The presented scientific review provides information on the structure and production of IgA both under normal and contributing to pathology conditions. The study examines the triggers of IgA1 underglycosylation, in particular, chronic nasopharynx and intestines diseases, the heterogeneity of the microbiota of these parts of the gastrointestinal tract, and food antigens. New data on the pathogenesis of IgA nephropathy underlie the developed and already tested methods of treating the disease and therefore may be of interest to clinicians. For example, a large international multi-center, randomized, double-blind, placebo-controlled NefigArd trial has demonstrated the effectiveness of a glucocorticoid drug (budesonide/Nefecon) with a targeted release in the ileum with a significantly lower incidence of adverse events in comparison to systemic corticosteroids.

Background. Paraprotein-related kidney damage in B-cell malignancies (BCM) often share common features with monoclonal gammopathy of renal significance (MGRS). In this single-center retrospective study, we aimed to analyze clinical presentation and pathology patterns of paraprotein-related kidney damage in malignant and non-malignant B-cell disorders. Materials and methods. Study group included 197 patients (M/F ratio 47.7/52.8%, mean age 59.41±10.44 years), with pathology-proven paraprotein-related kidney disease, followed in 1997-2022. For the further analysis, we split the patients into two sub-groups; MGRS sub-group consisted of 168 (85.2%) cases, and BCM sub-group included 29 (14.7%) cases. Results. In the MGRS sub-group general weakness, dyspnea, arterial hypotension, nephrotic syndrome and presence of monoclonal light chains lambda were found significantly more often compared to the BCM sub-group (p=0.011, p=0.009, p=0.010, p=0.011, and р=0.015 respectively). In the BCM sub-group significantly more often were arterial hypertension, presence of monoclonal light chains kappa and bone marrow plasmacytosis (p=0.048, р=0.003 and p<0.001 respectively). AL amyloidosis apparently dominated in the MGRS sub-group, constituting 72.6% of cases; in the BCM sub-group it was found in 31.0% of cases. Monoclonal immunoglobulin deposition disease was the more often finding in the BCM sub-group compared to MGRS (24.1% vs 11.3% respectively), however also yielding AL amyloidosis (24.1% vs 31.0% respectively). Cast-nephropathy, as well as light chain proximal tubulopathy, presented not exclusively in multiple myeloma, but also in the MGRS setting, but were both more than ten times often in BCM (13.7% vs 1.1% and 10.3% vs 0.5% respectively). Proliferative glomerulonephritis with monoclonal immunoglobulin deposits, atypical membranous nephropathy, cryoglobulinemic glomerulonephritis and C3 glomerulonephritis were found in MGRS sub-group only; and glomerulonephritis with antibodies to glomerular basement membrane. Non-proliferative glomerulonephritis with immunoglobulin M monoclonal deposits presented in the single cases in both sub-groups. Combination of two patterns of damage presented in BCM more than twice often, compared to MGRS (13.7% vs 5.3% respectively). Conclusions. AL amyloidosis, associated with monoclonal light chains lambda and presenting with general weakness, dyspnea, arterial hypotension and nephrotic syndrome is the most often pattern of paraprotein-related kidney damage, regardless malignant or non-malignant nature of the secreting clone; however, it is much more typical for MGRS than for BCM. Cast-nephropathy, traditionally regarded as a hallmark of multiple myeloma, also seen in smoldering myeloma, thus representing MGRS.

Introduction Vascular problems account for 10 % of the overall structure of renal allotransplantation complications [1]. These include transplant renal artery (TRA) thrombosis, renal vein thrombosis, TRA stenosis, renal vein stenosis, arteriovenous fistulas, and vascular pseudoaneurysms. 75 % of vascular complications are represented by TRA stenosis [1]. One of the reasons for the TRA stenosis formation in the late postoperative period is vascular atherosclerosis [2]. Stenosis most commonly develops in the TRA anastomosis with the external iliac artery (EIA) or in the TRA distal segment, less frequent in the ileorenal segment (in 1.5 % of cases) [3, 4]. When isolated stenosis occurs proximal to the TRA anastomosis with the iliac artery, the so-called TRA pseudostenosis develops [3]. The clinical picture of hemodynamic significant TRA stenosis is characterized by the presence of difficult-to-control arterial hypertension (AH) and/or progressive allograft dysfunction [1, 2]. Timely surgical correction leads to stabilization of blood pressure and renal transplant function. The method of choice for surgical correction is percutaneous endovascular intervention (PEI) with balloon angioplasty and/or stenting of the affected vessel [1, 3, 5]. Clinical case We present a case of a 66-year-old male patient with a history of polycystic kidney disease, frequent attacks of pyelonephritis, and drug-controlled hypertension. Since February 2011, end-stage renal failure developed and was treated with peritoneal dialysis. In June 2011, bilateral nephrectomy was performed, and in November 2011, renal allotransplantation was performed. Transplant function was immediate, creatinine levels remained between 110 and 130 μmol/L for more than 10 years. Since July 2023, swelling of the legs, complaints of weakness in the legs, pain in the right leg when walking, an increase in blood pressure to 180/100 mm Hg on the usual three-component antihypertensive therapy have appeared. In August 2023, creatinine increased to 180 µmol/l, urea - 14.9 mmol/l, daily proteinuria - 0.18 g. The patient admitted with decompensated hypertension and progressive transplant dysfunction. Doppler ultrasound (DUS) of the transplant vessels showed a moderate decrease in peak systolic velocity (PSV) of intraparenchymal blood flow, a change in the spectrum according to the type of poststenotic vasodilation (“tardus et parvus”) - indicators of the arterial resistance index (RI) 0.46-0.58, flow acceleration time 0.15-0.17 ms (Fig. 1A ). The area of anastomosis of the TRA with the EIA was unremarkable. The EIA is visible as a short fragment distal to the anastomosis with retrograde, monophasic, low-resistance blood flow (Fig. 1B ). A hemodynamically significant stenosis of the proximal fragment of the EIA was suggested. DUS of the right lower extremity arteries showed that against the background of multi-level hemodynamically significant atherosclerosis and calcification, collateral filling of the femoral-popliteal arteries, arteries of the lower leg, and dorsum of the foot is determined with a sharp decrease in velocity characteristics (PSV 10-20 cm/sec). Multispiral computed tomographic (CT) angiography was performed. A series of axial sections through the EIA in the arterial phase of contrast-enhanced CT showed the right EIA from the ostium to the TRA origin level with occlusion of the lumen against the background of massive atheromatous lesions (Fig. 2, a, b, c ). The 3D-reconstruction of the arterial phase of contrast-enhanced CT showed that there were right iliac arteries with atherosclerotic lesions of the walls (arrow indicates the occlusion zone), intact TRA (two arrows) (Fig. 1C ). Due to the confirmed critical stenosis of the EIA and clinical and instrumental signs of pseudo-stenosis of the TRA, a decision was made to perform direct angiography followed by PEI. The right femoral artery was punctured retrograde, and an introducer was installed. Retrograde angiography revealed chronic occlusion of the EIA, and an intact TRA was visualized below the occlusion (Fig. 3A ). The right brachial artery was punctured, an introducer was installed, a diagnostic catheter was inserted into the right common iliac artery, and antegrade angiography of the common iliac artery was performed: occlusion of the EIA from the ostium was confirmed and 90% stenosis of the ostium of the internal iliac artery was revealed (Fig. 3B ). A decision was made on retrograde endovascular recanalization of the occluded segment of the EIA. The guidewire was passed through the occlusion into the infrarenal aorta. Predilatation of the EIA stenotic lesion area with a balloon catheter was performed, and the EIA antegrade blood flow was obtained (Fig. 3C ). A peripheral stent was implanted into the area of EIA stenosis, and post-dilatation was performed in the stent with a 10.0 × 60 mm balloon catheter. The control angiogram demonstrated complete restoration of patency of the right EIA and satisfactory antegrade blood flow in the TRA (Fig. 3D ). After recanalization, the patient’s condition improved significantly: blood pressure levels normalized, transplant function was restored (creatinine 111 μmol/l), pain and weakness in the legs disappeared, pulsation appeared in a. dorsalis pedis. Control DUS demonstrated positive dynamics: velocity indicators of intraparenchymal blood flow increased, Doppler signs of post stenotic vasodilation were mitigated. Conclusion The presented clinical case demonstrates a rare variant of TRA pseudo-stenosis, which was caused by progressive multifocal atherosclerosis of the recipient arteries. Occlusion of the EIA resulted in retrograde blood supply to the allograft, its dysfunction, and refractory hypertension. Successful PEI with stenting made it possible to completely restore antegrade blood flow in the EIA occlusion area and normalize the blood supply to the transplant. The PEI resulted in restoration of transplant function, relief of AH and resolution of the symptoms of intermittent claudication. Informed consent was obtained from the patient for publication of clinical information and images.

Light chain proximal tubulopathy (LCPT) is a disease characterized by specific kidney damage due to the accumulation of abnormal monoclonal immunoglobulins (paraproteins, M-proteins), produced by B-cells or plasma cells clones, in the epithelium of the proximal tubules. LCPT is one of the patterns, representing a heterogeneous group of kidney diseases, caused by paraproteinemia [1]. Paraproteinemic nephropathies significantly differ in their clinical manifestations, prognosis, approaches to treatment, as well as in their histological manifestations. Most often, paraproteins are secreted by tumor cells in plasma cell myeloma. However, secretion of paraproteins has been described in B-cell lymphomas; monoclonal immunoglobulins secretion may also be driven by non-malignant B-cell or plasma-cell clones [2]. Kidney pathology in secreting plasma-cell dyscrasias includes several types of damage with different patterns and topographic involvement of the nephron through the deposition of monoclonal immunoglobulins or monoclonal light or heavy chains. LCPT is characterized by inclusions of monoclonal immunoglobulin light chains in the cytoplasm of the proximal tubules [1]. The crystalline form of LCPT is a kidney-limited form with crystal accumulation, and, most commonly, is caused by immunoglobulin kappa light chains [3]. The crystalline form of LCPT is characterized by extensive crystal formation in proximal tubular epithelial cells [1]. Of note, monoclonal immunoglobulins are resistant to proteolysis due to specific amino acid sequences [4]. Patient A, 42 years old, complained of large joint pain and the appearance of “foamy” urine for a year before admission. At admission work-up detected proteinuria up to 4.3 g/L, her serum total protein was 64 g/L, total cholesterol 6.02 mmol/L, and serum creatinine 216-229 µmol/L. After the nephrologist’s consult, the patient was referred to the nephrology unit. Her proteinuria was 1.288 g/day, and her serum creatinine was 146 µmol/L. Further work-up with serology tests ruled out connective tissue disorders, including SLE, ANCA-associated vasculitis, and rheumatism. A kidney biopsy was performed to verify the diagnosis. Microscopic examination revealed 15 otherwise normal glomeruli. The cytoplasm of the convoluted tubules epithelium contained coarse eosinophilic granules, with evidence of necrotic lesions of some epithelial cells: cytosome appearance and detachment from the basement membrane. An immunofluorescent study on fresh frozen sections found 4 glomeruli with negative reactions with antibodies to IgA, IgM, C3c, IgG, C1q, kappa, and lambda light chains. In the tubular epithelium, granular cytoplasmic expression was determined by immunohistochemical study with antibodies to lambda light chains, and no expression with antibodies to kappa light chains. Electron microscopy showed normal glomeruli; the cytoplasm of some epithelial cells and tubular lumens contained inclusions of uneven (low and moderate) electron density, medium or large size, irregularly elongated, diamond-shaped, and leaf-shaped. These findings were compatible with the diagnosis of the crystalline form of proximal light chain tubulopathy. An additional workup found Bence-Jones protein lambda in the urine. The bone marrow smear revealed 21% of plasma cells with signs of dysplasia. The final diagnosis was as follows: Multiple myeloma IIB according to Durie-Salmone, with the secretion of Bence-Jones protein lambda. Light chain proximal tubulopathy, crystalline form, CKD stage G3A. The patient was referred to the hematology unit for chemotherapy. None of the authors declare a conflict of interests.

Despite the obvious advantages of an arteriovenous fistula, the tunneled central venous catheter (tCVC) remains a first-line vascular access in a significant number of incident patients. The formation of a fibrin sheath (FS) around the intravascular segment of the dialysis catheter is a consequence of the pathophysiological interactions of the abiotic artificial structure with the venous endothelium and blood cells. In some cases, FS remains in the central vein lumen after removal of the dialysis catheter, mimicking the structure and contour of the fragment of the extracted tCVC (“ghost” catheter). FS of the removed tCVC is usually asymptomatic, is an accidental diagnostic finding and does not require special medication or surgical intervention. Nevertheless, the contribution of the “ghost” catheter in the development of specific infectious and non-infectious complications seems to be underestimated. In particular, FS of the removed tCVC can become a nidus of the nonvalvular right-sided infective endocarditis or a source of thromboembolic complications. The article provides an overview of current state of the art regarding the morphology of FS, the optimal diagnostic modalities of it’s visualization, possible FS-associated complications and approaches to their treatment. The article is supplemented by own clinical observations and is addressed to a wide range of health professionals dealing with vascular access for maintenance hemodialysis.

Membranous nephropathy (MN) is a variant of glomerulopathy characterized by diffuse thickening and restructuring of the glomerular basement membrane as a result of subepithelial and intramembranous deposition of immune complexes and deposition of matrix material produced by affected podocytes. MN is one of the most common causes of nephrotic syndrome in adults (20-40% of cases). Secondary MN develops against the background of autoimmune diseases, tumors, infections, drug exposures, etc. The determination of antibodies to PLA2R can be used as an informative test for the diagnosis of MN and the differential diagnosis of its primary and secondary forms. It is known that antibodies to PLA2R are detected in 70-80% of patients with primary MN. In secondary MN, detection of antibodies to PLA2R is rare, and a feature of this clinical observation is the anti-PLA2R positivity of our patient. The article describes a clinical observation of a 69-year-old patient with nephrotic syndrome, with a morphologically confirmed diagnosis of MN and the detection of anti-PLA2R antibodies. However, a secondary genesis of MN was established. During the diagnostic search, the main causes of secondary MR were excluded. The reason for the development of secondary MR, in this case, was chronic recurrent cholangitis against the background of stricture of the common bile duct with frequent exacerbations. Descriptions of MN against the background of autoimmune diseases of the hepatobiliary system can be found in literature, but not often. Cases of association of MN with chronic cholangitis of bacterial origin have not been described yet, but there are isolated observations of secondary MN against the background of other bacterial infections. Despite the detection of antibodies to PLA2R and morphological confirmation of MN, immunosuppressive therapy was not performed in this patient due to the risk of developing septic complications and the supposed secondary nature of nephropathy. The patient was recommended surgical treatment. After endoprosthesis replacement of the choledochus the patient's condition improved, nephrotic syndrome regressed and the level of antibodies to PLA2R decreased significantly, which confirms the secondary genesis of the disease.