Kidney disease is an important public health problem. Both acute kidney injury (AKI) and chronic kidney disease have been well defined and classified, leading to improved research efforts and subsequent management strategies and recommendations. For those patients with abnormalities in kidney function and/or structure who meet neither the definition of AKI nor chronic kidney disease, there remains a gap in research, care, and guidance. The term acute kidney diseases and disorders, abbreviated to acute kidney disease (AKD), has been introduced as an important construct to address this. To expand and harmonize existing definitions and to ultimately better inform research and clinical care, Kidney Disease: Improving Global Outcomes (KDIGO) organized a consensus workshop. Multiple invitees from around the globe, representing both acute and chronic kidney disease researchers and experts, met virtually to examine existing data, and discuss key concepts related to AKD. Despite some remaining unresolved questions, conference attendees reached general consensus on the definition and classification of AKD, management strategies, and research priorities. AKD is defined by abnormalities of kidney function and/or structure with implications for health and with a duration of £3 months. AKD may include AKI, but, more importantly, also includes abnormalities in kidney function that are not as severe as AKI or that develop over a period of >7 days. The cause(s) of AKD should be sought, and classification includes functional and structural parameters. Management of AKD is currently based on empirical considerations. A robust research agenda to enable refinement and validation of definitions and classification systems, and thus testing of interventions and strategies, is proposed.

As the rate of natural disasters and other devastating events caused by human activities increases, the burden on the health and well-being of those affected by kidney disease has been immeasurable. Health system preparedness, which involves creating a resilient system that is able to deal with the health needs of the entire community during times of unexpected disruptions to usual care, has become globally important. In the wake of the COVID-19 pandemic, there is a heightened awareness of the amplification of negative effects on the renal community. Paradoxically, the complex medical needs of those who have kidney diseases are not met by systems handling crises, often compounded by an acute increase in burden via new patients as a result of the crisis itself. Disruptions in kidney care as a result of unexpected events are becoming more prevalent and likely to increase in the years to come. It is therefore only appropriate that the theme for this year’s World Kidney Day will focus on Kidney Health for All: preparedness for the unexpected in supporting the vulnerable.

Secondary hyperparathyroidism (HPT) in patients with chronic kidney disease (CKD) is part of the syndrome of mineral-bone disorders associated with CKD (MBD-CKD), which is a systemic disorder of mineral and bone metabolism. The development of the disease is closely associated with the loss of renal functions, leading to complex disorders in the metabolism of calcium, phosphorus, vitamin D, excessive secretion of fibroblast growth factor 23 (FGF23), and a decrease in renal expression of its membrane co-receptor αKlotho. All these disorders, as well as an altered skeletal response to the action of PTH, stimulate the synthesis and secretion of PTH in the PTG, followed by their diffuse, diffuse-nodular hyperplasia and a progressive decrease in the expression receptors on the surface of the gland. There is new information about the molecular mechanism of αKlotho/FGF23 and the Wnt/β-catenin signaling, which may contribute to the development of CKD-associated HPT. Secondary HPT is a common complication of CKD, which significantly impairs the quality of life of patients, complicates the implementation of kidney transplantation, leads to repeated hospitalizations, and increases mortality. In the Russian dialysis population, secondary HPT is detected in 54.8% and 28.6% of patients, respectively, with diagnostic criteria PTH >300 pg/ml and PTH >600 pg/ml. The disease has a systemic character and is manifested primarily by musculoskeletal and cardiovascular pathology and other extraskeletal disorders. The diagnosis of secondary HPT is based on the simultaneous assessment of the main biochemical markers of the disease - PTH, calcium, phosphorus, and alkaline phosphatase, studied over time, and the identification of trends in these markers. The diagnostic serum PTH level for secondary HPT in non-dialysis CKD remains unknown, in dialysis patients more than 4-6; in some cases, more than 9 upper limits of the reference interval are recommended. A variety of instrumental methods is used for detecting bone and cardiovascular pathology: plain radiography, dual-energy x-ray absorptiometry, variants of computed and magnetic resonance imaging, bone biopsy, and ultrasound. PTG visualization is carried out by ultrasound, computed tomography, 99mTc-sestamibi scintigraphy photon emission computed tomography; it is indicated for patients with severe HPT requiring surgical treatment.

Background: patients with Diabetes Mellitus 2 (DM2) and advanced stages of Diabetic Kidney Disease (DKD) are at high risk for the lethal outcome of COVID-19. The causes of high mortality and the prognostic significance of the new onset of renal replacement therapy (hemodialysis de novo, HD de novo) among these patients are still points of debate. Aim: the identification of risk factors (RF) of lethal outcome in patients with DKD 4-5D stages and evaluation of the prognostic value of HD de novo in patients not receiving HD at the time of hospital admission. Methods: the patients with COVID-19 and advanced stages of DKD were included in a retrospective observational study from 04.01. to 10.30.2020. The endpoints were the outcome of hospitalization (discharge/death) and HD de novo initiation during the inpatient course. Several demographic, DM2, DKD, and COVID-19-associated signs and laboratory parameters were analyzed as independent variables. The subgroup of patients with HD de novo was selected from the general cohort. Results: 120 patients with DKD 4-5D stages were included, with a mean age of 69±10 y, females - 52%. Initially, the observation cohort was divided into subgroups: DKD 4-5 and DKD 5D on maintenance hemodialysis (MHD). The mortality among patients with DKD 4-5 was comparable with the patients on MHD (38,2% vs 38,5%, р=0,975). The independent predictors of lethal outcome in group DKD 4-5 were: age ≥65 y (OR 12,30; 95% CI 1,40-33,5; р=0,009), initial prandial glycemia ≥10 mmol/l (OR 14,5; 95% CI 3,7-55,4; р<0,001), albuminemia at admission ≤35 g/l (OR 5,17; 95% CI 1,52-17,50; р=0,012), Charlson comorbidity index (CCI) ≥10 (OR 6,69; 95% CI 1,95-23,00; р=0,002), News2 >4 at admission (OR 7,58; 95% CI 2,18-26,37; р=0,001), lung damage CT 3-4 at admission (OR 3,39; 95% CI 1,09-10,58; р=0,031). In subgroup DKD 5D the independent predictors of lethal outcome were prandial glycemia at admission ≥10 mmol/l (OR 28,5; 95% CI 7,1-33,5; р<0,001), lung damage at admission CT 3-4 (OR 8,35; 95% CI 2,64-26,40; р<0,001), CCI ≥10 (OR 6,00; 95% CI 1,62-22,16; р=0,006). To determine the risk of lethal outcome predictive models were created using identified risk factors and variables. The predictive value for DKD 4-5 group was 93%, and for DKD 5D was 88%. The assessment of the overall predictive value of these models was carried out using ROC analysis. The mortality among patients with DKD 4-5 without HD de novo was 21,6% vs 72,2% in patients with initiated HD de novo (р<0,001). The independent predictors of HD de novo during the inpatient course were: prandial glycemia at admission ≥10 mmol/l (OR 3,38; 95% CI 1,04-10,98; р=0,050), albuminemia at admission ≤35 г/л (OR 3,41; 95% CI 1,00-11,55; р=0,050), News2 >4 at admission (OR 5,60; 95% CI 1,67-19,47; р=0,006), eGFR ≤20 ml/min/1,73 m2 at admission (OR 4,24; 95% CI 1,29-13,99; р=0,020). HD de novo was identified as an independent predictor of adverse outcomes (OR 9,42; 95% CI 2,58-34,4; р=0,001). The analysis of cumulative survival demonstrated comparable results in DKD 4-5 without HD de novo group and DKD 5D group. The cumulative 55-day survival in the subgroup with HD de novo was only 10%. Conclusion: the need to start HD de novo is one of the most powerful predictors of adverse outcomes of COVID-19 in patients with advanced DKD. The comparable mortality rate in DKD 4-5 and DKD 5D groups is due to extremely high mortality in the subgroup with HD de novo. The strict control and correction of HD de novo risk factors could turn them into modifiable ones and thus improve the survival prognosis of patients with advanced stages of DKD.

Idiopathic infantile hypercalcemia, type 1 (IIH1) is a rare autosomal recessive disorder characterized by hypercalcemia, low parathyroid hormone (PTH) serum level, hypercalciuria, nephrocalcinosis (NC), and/or urolithiasis. IIH1 caused by mutations in the CYP24A1 gene that encodes a key enzyme responsible for the catabolism of active vitamin D. Aim: to evaluate clinical features and molecular characteristics of IIH1 in Russian children and search for phenotype features of the disease in children with their age and potential genotype-phenotypic associations. Materials and methods: we conducted a retrospective two-center longitudinal study of 20 children (9M/11F) with genetically confirmed IIH1. The median age of patients at the beginning of follow-up was 13 [10.0; 58.5] months. Genetic analysis was performed in all children using by next generation sequencing technology - complete exome sequencing (n=7), clinical exome sequencing with the study of mutations in 22 genes associated with rickets-like diseases (n=11), and direct automatic sequencing of the CYP24A1 gene (n=2). To identify age-related features of IIH1, patients were divided into 2 groups depending on their age at the time of the initial examination before diagnosis: group 1 included children <24 months (n=12), and group 2 - children ≥24 months (n=8). Results: the most prevalent features of IIH1 were medullary NC (100%) and low PTH serum level (90%). Hypercalcemia was found in 75% of children, hypercalciuria in 60% of patients, and urolithiasis in 20% of the children. According to the results of a molecular genetic study, the most common CYP24A1 variants were p.Arg396Trp (55%) and p.Glu143del (40%). Also 4 novel CYP24A1 variants were identified: p.Gly78Val, p.Arg396Gln, p.Met99Thr, p.Gln471SerfsTer21. In patients examined up to 24 months, serum levels of calcium (Ca2+ and total) were higher: 1.39 [1.35; 1.56] mmol/l vs. 1.31 [1.24; 1.34] mmol/l (p=0.013) and 2.9 [2.71; 3.74] mmol/l vs. 2.45 [2.36; 2.52] mmol/l (p=0.001), respectively, and serum level of PTH was lower: 7.9 [3.0; 12.7] pg/ml vs. 14.6 [8.25; 15.85] pg/ml (p=0.038) than in older children. Conclusion: a greater awareness of IIH1 phenotypes will increase clinical suspicion in patients presenting with NC or hypercalcemia. Testing for mutations in the CYP24A1 gene can establish a definitive diagnosis and clinical management by minimizing vitamin D intake to prevent the effects of vitamin D toxicity and dietary and lifestyle advice.

Aim. To analyze the first experience of using transluminal balloon angioplasty (TBA) in the treatment of central vein stenosis (CVS), arteriovenous fistula (AVF) stenosis, to evaluate the safety and efficacy of this technique, to study the long-term consequences of balloon angioplasty. Material and methods. From January 2020 to July 2022, 71 endovascular balloon angioplasty procedures were performed to treat vascular access dysfunction. In 30 (42%) patients who made up the first observation group, the cause of vascular access (VA) dysfunction was CVS, in 41 patients (58%), who made up the second observation group, the cause of dysfunction was AVF stenosis. In each of the groups, we assessed the immediate and long-term results of balloon angioplasty in terms of technical effectiveness (the possibility of passing through the zone of stenosis with a wire guide and performing TBA), technical success (less than 30% residual stenosis after TBA), recurrence rate, and primary AVF patency. Results. In the first group (CVS), the median percentage of stenosis before the intervention was 90 (IQR: 80-95)%, and after angioplasty it was 25 (IQR: 15-45)%. Technical efficiency was 93.3% (28/30), and technical success was 53.3% (16/30). The primary patency of the central vein within 3, 6, and 12 months was 87.2%, 74.5%, and 39.0%, respectively. In the second group (AVF stenosis), the median percentage of stenosis before the intervention was 80 (IQR: 75-90)%, and after angioplasty it was 10 (IQR: 0-30)%. Technical efficiency was 95.1% (39/41), technical success was 82.9% (34/41). Primary AVF patency within 3, 6, and 12 months was 85.7%, 82.4%, and 77.8%, respectively. Conclusion. Transluminal balloon angioplasty has proven to be a safe and effective treatment for central venous stenosis and arteriovenous fistulas. Performing both primary and repeated TBA procedures in most cases allows prolonging the use of the existing permanent vascular access (AVF) without performing repeated operations, and thus allows for saving vascular resources in the future.

Introduction The incidence of renal cell carcinoma (RCC) in kidney transplant (KT) recipients is about 0.6%. This rate is 10 times higher than in the general population [1]. The causes of the high risk of developing RCC in KT are not completely clear and a connection with ongoing immunosuppressive therapy (IST) is highly likely [1, 2]. The detection of VHL and MET mutations in the genomes of the donor and recipient are of great practical significance to clarify the molecular and genetic mechanisms of the progression of clear cell and papillary RCC in KT [3]. To date, about 200 cases of allograft RCC have been described worldwide [1, 2]. Usually, most KT neoplasms are detected incidentally during routine ultrasound examination (USE) [1, 2, 4, 5]. The priority treatment strategy is the nephron-sparing surgery of KT malignant neoplasms [1, 2, 4, 5]. Despite the increasing number of publications, this issue is not widely covered and is still a point of debate. Clinical case The 41-years old male has been hospitalized with severe course of Covid-19 and KT dysfunction. His medical history was remarkable with end-stage renal failure due to chronic glomerulonephritis, a long period of maintenance hemodialysis, and cadaveric kidney allotransplantation in 2014. Serum creatinine (Pcr) at admission was 240 µmol/l. A rounded hypoechogenic solid poorly demarcated formation sized 2.7×3.0 cm and of the heterogeneous structure was detected near the renal sinus during routine USE ( Fig. 1A). Color Doppler mapping demonstrated the preserved blood flow in KT, but in the detected formation the blood flow was almost absent. In process of recovery from COVID-19 Pcr diminished to the patient’s usual values (150 µmol/l). To clarify the origin of KT formation and to exclude the possible metastases multispiral computed tomography with contrast enhancement was performed. A hypovascular mass was revealed and papillary RCC was suspected according to special contrast features. An object of 3.0×2.8×2.3 cm with an uneven accumulation of the contrast media (45-68 HU) in the middle third of KT is shown in Fig. 1B. The patient underwent laparoscopic partial nephrectomy. Intraoperative USE was performed using an intracorporeal ultrasonic transducer to localize the tumor and to outline the resection area ( Fig. 1C). Temporary stoppage of blood flow in the KT was carried out by applying the Blalock vascular clamp to the right external iliac artery. The intraoperative picture of allograft formation along the posterior surface of the kidney is shown in Fig. 2A. The operating time was 165 minutes, the time of KT ischemia was 21 minutes, and the volume of blood loss was 240 ml. Fig. 2B shows a resected KT tumor, histological examination of the tumor revealed papillary RCC type 1, ISUP grade 2, pT1aNoMoR0 ( Fig. 2C). The postoperative period was uneventful, and Pcr 14 days after surgery was 142 µmol/l. Conclusion A laparoscopic partial nephrectomy is a nephron-sparing approach to surgical treatment of RCC of the KT. The presented clinical case demonstrates the possibility and advantages of minimally invasive radical elimination of a malignant tumor. Such an approach allows for saving the KT function, decreases the risks of septic and hemorrhagic complications, and significantly reduces the time of hospitalization.

Townes-Brocks syndrome (TBS, OMIM #107480) is a rare disease with autosomal dominant inheritance caused by pathogenic variants in the SALL1 gene. TBS is characterized by a variable combination of congenital anomalies, the major of which are imperforate anus, dysplastic ears, and thumb malformations. Due to the essential role of SALL1 in kidney development as a transcription factor, congenital anomalies of the kidney and urinary tract (CAKUT) could be also observed in patients with TBS. They belong to the minor signs of the syndrome, such as hearing loss, foot malformations, ocular features, and congenital heart disease. In this article, we present a clinical observation of a child with renal involvement as an exhibition of TBS with the absence of the full classical triad. The child had only one (bifid thumb) out of 3 major features, 2 minor signs (bilateral kidney hypoplasia, iris defect), and tubular dysfunction (low-molecular proteinuria, glucosuria). Progression to CKD grade 3а (eGFR 52 ml/min/1.73 m2) in the index case was remarkable. The whole exome sequencing identified a novel heterozygous nonsense variant (chr16:51175421G>A) с.712С>T (p.Gln238Ter) in the SALL1 gene, which was validated by Sanger sequencing, and diagnosis of TBS was confirmed. The same SALL1 variant (chr16:51175421G>A) was identified in her mother with a combination of clinical futures of the syndrome, such as bilateral kidney hypoplasia with decreased glomerular filtration (eGFR 40.3 ml/min/1.73 m2), that suggested a familiar case of TBS.

A patient receiving treatment with maintenance hemodialysis underwent many unsuccessful attempts of arteriovenous fistula creation. Central venous catheters were implanted into the central veins of the chest; iliac veins remained the only stable type of vascular access in him. A further dysfunction required the implantation of a new catheter. The examination revealed that the right and left jugular veins were partially occluded, the brachycephalic vein was not passable, the right and left iliac veins were partially occluded, and the inferior vena cava was completely patent. Conversion of renal replacement therapy to peritoneal dialysis was impossible due to pancreatic necrosis and peritonitis in the past. Any attempts of endovascular recanalization of the brachiocephalic vein did not succeed. According to vital indications, a tunneled catheter was implanted into the inferior vena cava through retroperitoneal pararectal access in the right iliac region. Due to partial occlusion of the right common iliac vein, a catheter was implanted in the unification of the common iliac veins. The lumen of the vein was sealed around the catheter, the latter was additionally fixed to the rectus abdominis muscle aponeurosis, and the dacron cuff was attached to the external oblique abdominal muscle aponeurosis to ensure its optimal position. The catheter was placed on the anterior wall of the abdomen through the contraperture, and the blood flow was adequate. At the 6 months follow-up, the patient's condition was stable, the catheter was working properly.