The course of the COVID-19 pandemic has led to a critical increase in the burden on virtually all major branches of the health care system in our country and abroad.

   The aim of this article is to analyse the activities of the different parts of the city nephrol­ogy service in Saint-Petersburg and to consider promising ways to improve it.

   The nephrology service for the adult population in St. Petersburg includes: outpatient service; inpatient service - 183 beds in 24-hour inpatient departments of the city; dialysis service - 10 dialysis units in municipal medical organizations, 5 in federal institutions, and 8 centers/departments operating in the framework of private-public partnership. The number of patients on dialysis programme decreased by 10.5 % to 1,839 in 2021. These changes are likely due to an increase in mortality among these patients in 2020 and 2021 which is a consequence not only of COVID-19 but also of the adverse impact of the pandemic on the health system. The proportion of patients treated as outpatients in private dialysis centres increased during the three-year period. The incidence of arteriovenous fistula formation in primary vascular access decreased from 33.2 % to 14.2 % in 2020 compared with 2019. At the same time, the use of temporary central venous catheters as primary vascular access for renal replacement therapy has increased significantly from 43.0 % to 61.9 %. The development of the nephrology service is largely determined by its funding. To compensate the costs of medical in­ stitutions in the city for conducting renal replacement therapy it is necessary to increase the tariffs of compulsory health insurance (CHI) by at least 50 %. In the medical organizations of Saint-Petersburg municipal and federal subordination the share of "artificial kidney" devices that have used up their resource is 32.2 %, and in a number of medical institutions it exceeds 50 %.

   This review presents the latest data on the classification, pathogenesis, clinical and genetic features, and therapy of primary hyperoxaluria types I, II, and III in children with autosomal recessive inheritance. ORPHA portal of orphan diseases presents genes responsible for primary hyperoxaluria type I AGXT (93598); type II and type II GRHPR (93599), type III HOGA1 (93600). Worldwide genetic studies have established the pathogenesis, clinical phenotype and genotype features of primary hyperoxaluria. The pathogenesis of primary hyperoxaluria in children is based on impaired hepatic glyoxylate metabolism. The enzyme AGT catalyzes the conversion of L-alanine and glyoxylate to pyruvate and glycine, with vitamin B6 (pyridoxine) serving as a coenzyme for this reaction. Increased production of endogenous oxalate leads to increased blood oxalate concentrations and urinary oxalate excretion with the formation of renal calcium oxalate crystals and radiopaque concrements (calcium oxalate monohydrate – vevelite, calcium oxalate dihydrate – vedellite). High risk of progression to chronic kidney disease in primary hyperoxaluria in children of types I and II. Systemic oxalosis develops with increasing serum oxalate levels and the formation of calcium oxalate crystals with deposition in many organs and tissues. Therapy for primary hyperoxaluria in children includes: hydration (3l/m²/day) and citrates 100–150 mg/kg/day (potassium citrate 0.3–0.5 mmol/kg/day), pyridoxine at a dose of 5 to 20 mg/kg/day for vitamin B6 sensitive type I primary hyperoxaluria. Administration of oxalobacter formigenes and diet is effective. Combined liver and then kidney transplantation or simultaneous liver and kidney transplantation in patients with type I PH in B6-insensitive and isolated liver transplantation in B6-sensitive variants are performed. Timely molecular genetic testing in children with nephrocalcinosis makes it possible to establish a clinical and genetic diagnosis of type I, II, III PH, to carry out a personalised approach to treatment and to predict future health status.

   The review presents material on the current relevance of AH in children. The prevalence of AH in overweight and obese children aged 6-18 years is 27–47 %, while secondary arterial hypertension remains dominant, especially in children younger than 5 years. AH is a major risk factor for atherosclerosis and cardiovascular disease in adults. The onset of these diseases may occur in childhood or adolescence. The use of modern methods to monitor and control BP is crucial for improving the management of AH and preventing damage to target organs. Twenty-four-hour BP measurements are an important tool in determining the prognosis and treatment of children with AH. AH in children can be classified as primary or essential if there is no identifiable cause, or as secondary AH when it arises from a specific cause. The incidence of primary arterial hypertension increases with age, whereas secondary arterial hypertension predominates in early childhood. The secondary causes of AH also depend on the age of the patient. Thus 34-79 % of patients with secondary forms of arterial hypertension have renal parenchymal disease and impaired renal structure. Signs of AH include headache, visual disturbances, dizziness and nosebleeds. Dyspnoea on exercise, facial paralysis and seizures indicate target organ damage. In children with obesity, diabetes, renal insufficiency, aortic coarctation/repaired coarctation and those receiving medication causing AH, BP should be measured at every visit to the physician. Therapeutic lifestyle changes are an early therapy in the treatment of AH in children. IAPs, BCAAs, BRAs and thiazide diuretics are the most effective drugs for AH in children.

   BACKGROUND. Primary focal segmental glomerulosclerosis (FSGS) and membranous nephropathy (MN) are diseases with primary podocyte damage with high proteinuria and nephrotic syndrome. While the mechanisms in primary MN are well understood, the pathogenesis of primary FSGS is still unknown, and therefore, the search for biomarkers that could expand our
understanding of its pathogenetic mechanisms.

   THE AIM: to determine the urine proteomic profile of patients with primary podocytopathies – FSGS in comparison with MN.

   PATIENTS AND METHODS. The study included 48 patients with a morphologically confirmed diagnosis of CGN occurring with nephrotic syndrome – 32 men and 16 women. In 18 patients, a decrease in glomerular filtration rate < 60 ml/min/1.73 m² was observed. The histological diagnosis was confirmed by biopsy: 31 patients had FSGS, 17 patients with MN were included as a comparison group. The study of the urinary proteome was carried out by high performance liquid chromatography/mass spectrometry. RESULTS. In patients with FSGS, compared with the MN group, an increased content of 22 different proteins was noted, the most abundant were apolipoprotein A-I, hemopexin, vitronectin, pigment epithelial growth factor, components of the complement system (C3, C4b, factors B and H), retinol – and vitamin D-binding proteins, alpha-2-HS-glycoprotein, histidine-rich glycoprotein, plasma C1 protease inhibitor. In MN, increased urinary excretion of the complement component C2, fibrinogen alpha chain, osteopontin, and the SH3 domain-binding glutamic acid-rich-like protein 3, was detected.

   CONCLUSION. The proteomic profile of urine in FSGS, compared to MN, reflects the activation of variety of pathological processes – podocyte damage, involvement of parietal epithelial cells, tubulo-interstitial damage, accumulation of extracellular matrix, and complement activation process.

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   BACKGROUND. Hyperphosphatemia in CKD is spread widely, represents as independent factor of mortality at all stages of CKD, after transplantation, reduces the effectiveness of nephroprotection, leads to vascular calcification, stimulates hyperparathyroidism. Achieving the phosphatemia target is a difficult task and is based on a combination of a hypophosphate diet, effective dialysis, the antihyperparathyroidic measures and the phosphate-binders (PBs).

   THE AIM. The aim is to evaluate the effectiveness of sevelamer
therapy in real clinical practice as part of a hypophosphatemic strategy with clarification of the conditions and measures under which it is optimal.

   PATIENTS AND METHODS. In an eight-month study in a region where there are no restrictions on access to calcium-free PBs, 127 patients were included in the study after the "washing period ": the of sevelamer doses were titrated until phosphatemia reaches below 1.58 mmol/l in parallel with individual measures of four-component hypophosphatemic strategy.

   RESULTS. From the starting dose of 3-6 tablets/day, 38 patients experienced either dose increase (+ 1016 ± 760 mg) or in 28 patients
– decrease (- 1427 ± 1059 mg). By the third month of therapy, the proportion of patients with phosphatemia < 1.58 mmol/l reached 70 %, < 1.78 mmol/l – 90 %. The decrease magnitude depended on the initial phosphatemia, the level of PTH (maximum in the range of 150-600 pg/ml), occurs more slowly in men. During therapy, there was a decrease in the need for antihyperparathyroid therapy in the absence of dynamics in the parathyroid hormone level. In multiple regression analysis models, the independent factors associated with phosphatemia during treatment were sevelamer dose, dialysis dose, baseline phosphate and parathyroid hormone levels; the magnitude of phosphatemia reduction was independently associated with sevelamer dose, dialysis dose, baseline parathyroid hormone level, and assessment of treatment compliance.

   CONCLUSION. Sevelamer in a moderate well–tolerated doses as part of an individualized hyperphosphatemia correction strategy is able to achieve target phosphatemia (< 1.58 mmol/L) in 70 % of cases, and relatively safe level (< 1.78 mmol/L) – in 90 %.

   BACKGROUND. To date, the mechanisms of small stone elimination by lithokinetic therapy (LCT) have not been elucidated.
   THE AIM of this investigation was to estimate the activity of receptors controlling the contraction and relaxation of smooth muscle cells (SMC) against the background of α_1A-adrenoreceptor blockade during LCT in patients with small stones localization in the middle third of ureter.

   PATIENTS AND METHODS. The study was prospective and included 40 patients in whom standard LCT was done for localization of small concrements (≤6 mm) in the middle third of ureter. The functional activity of receptors modulating ureteric peristalsis was analyzed in vitro using platelet suspension. The agonists used were ATP, ADP, adenosine, epinephrine, angiotensin-2 (Sigma-Aldrich Chemie GmbH, Germany) at EC₅₀ concentrations causing aggregation at 50 % in healthy subjects. Platelet aggregation was assessed by turbidimetric method on ChronoLog analyzer (USA).

   RESULTS. No differences in the rate of small concrements elimination from the middle third of ureter was found in presence and absence of α_1A-adrenoreceptor blocker in LCT. Before LCT, α₂-adrenoreceptor hyperresponsiveness, normoreponsiveness of purine P2X1- and P2Y-receptors, adenosine A2-receptor and angiotensin AT1-receptor were found. After 9 days of LCT with verified elimination of concrements, an increase in P2X1-receptor and AT1-receptor activity (p < 0.001) was found regardless of the administration of α_1A-adrenoceptor blocker. P2Y-receptor hyperresponsiveness was seen in the presence and normoreponsiveness in the absence of α1A-adrenoreceptor blocker in LCT.

   CONCLUSION. At the lithokinetic therapy irrespective of α_1A-adrenoreceptor blocker prescription, compensatory mechanisms, aimed at enhancement of contractile activity and preservation of smooth muscle cell relaxation take part in the traffics of small concrements from the middle third of ureter.

   BACKGROUND. Chronic kidney disease leads to increased bone fragility and fractures. Assessing the risk of fractures is a direct way to prevent them.

   THE AIM: to assess the possibility of using DXA to predict fracture risk in patients with stage 5D CKD.
   PATIENTS AND METHODS. The prospective cohort study included 359 patients (166 men, 193 women). BMD was evaluated by DRA. Some markers of mineral and bone metabolism were also analyzed. All fractures in patients were recorded from the moment of inclusion in the study.

   RESULTS. All patients with fractures had lower BMD and received longer-term renal replacement therapy (RRT). The absolute risk of fractures increased as BMD decreased. Patients with fractures had higher levels of parathyroid hormone and alkaline phosphatase. Stepwise multivariate regression analysis showed that the combination of BMD scores of the forearm, hip, lumbar vertebrae and the duration of RRT best predicts the risk of fractures. The presence of previous fractures also increases risk for the future. Risk of fractures in man and women did not differ.

   CONCLUSION. The risk of fractures in patients with CKD 5 st. on maintenance hemodialysis increases with a decrease in BMD, an increase in the duration of RRT and the presence of previous fractures, but does not significantly depends on the gender of the patients. It is also can be concluded that it is possible to use criteria reflecting the state of BMD, taking into account their sensitivity and specificity, in assessing the risk of fractures in patients with CKD 5D st.

   BACKGROUND. Assessment of physical performance in patients is usually based on the results of the 6-minute walk test, which is primarily associated with heart or respiratory failure.

   THE AIM: to analyze the results of the 6-minute walk test with clinical and laboratory parameters of patients with CKD 5D, including criteria for protein-energy malnutrition.

   PATIENTS AND METHODS. 67 people with CKD 5D were examined, including 42 men and 25 women, mean age 49.0 ± 14.9 and 57.2 ± 15.5 years, respectively, p = 0.036. The duration of RRT in men was 96.1 ± 80.3 months, in women 100.7 ± 66.1 months, p = 0.810. The diagnosis of coronary heart disease was established in 22 people, 7 of them had AMI. The muscle strength of the skeletal muscles was assessed using a hand dynamometer, the performance of the skeletal muscles – during a test with a 6-minute walk. All patients filled out food diaries, where they indicated the qualitative and quantitative composition of the food which they consumed for 3 days.

   RESULTS. Walking load was most easily tolerated by patients without clinical manifestations of CAD. Between patients with and without AMI in history, the number of points on the Borg scale was comparable and reached the maximum values. The highest concentration of C-reactive protein and the lowest concentration of serum albumin were observed in patients who had had AMI. Relationships were found between serum albumin with C-reactive protein and the results of the 6-minute walk test, as well as between the mass index of the left ventricular myocardium with the results of the 6-minute walk test.

   CONCLUSION. Left ventricular hypertrophy masks the clinical signs of reduced physical performance, but increases the risk of cardiovascular complications. The results of the 6-minute walk test in patients with CAD should be evaluated in more detail. A number of studies are needed to clarify how dietary recommendations should be modified depending on the level of systemic inflammation in CKD.

   BACKGROUND. Chronic kidney disease (CKD) is a common pathology influencing mortality risk in the world population. Calcification of aorta and heart structures (valves, coronary arteries) is a risk factor for cardiovascular complications. The influence of cytokines, integrin proinflammatory indices, acute phase proteins and other inflammatory factors on the risk of extravasal calcification is promising.

   THE AIM: to study the effect of cytokines, integrative proinflammatory indices, acute phase proteins and other inflammatory factors on the risk of extra-osseous calcification.

   PATIENTS AND METHODS. A one-stage, cohort study of 85 patients with CKD 5D treated with programmed hemodialysis was conducted. General clinical examination was carried out according to the protocol. Blood levels of C-reactive protein (CRP) were determined by immunoturbodimetry. A Glasgow Prognostic Score (GPS) risk index for systemic inflammation was calculated using CRP and plasma albumin concentrations. Interleukin-6 (IL-6), interleukin-3 (IL-3) were assessed by enzyme immunoassay. Blood leukocyte shift index (BLI) was calculated. Echocardioscopy was performed using Doppler mode. The presence of cardiac valve calcification (CAC) was registered, its severity was assessed. To estimate the abdominal aortic calcification, the abdominal radiography was carried out in the left lateral projection. The severity of manifestations of aortic calcification was assessed using the L.I. Kauppilla Calcification Scale. Statistical analysis was performed using STATISTICA 12.6. toolkit (StatSoft, USA).

   RESULTS. Systemic inflammatory factors negatively affected the severity of cardiovascular calcification. An increased GPS value was found to correlate with the severity of CAC and CSA. In the case of calcification severity analysis considering IL-3 and IL-6 values, it was also shown that high levels of these pro-inflammatory cytokines are associated with severe manifestations of anterior aortic wall calcification and aortic calcification at the L3 level. Inclusion of ISLC in the analysis had no effect on the severity of calcification of the aortic wall and no effect on the intensity of cardiac valve calcification in general, the aortic valve and the mitral valve in particular.

   This article presents the features of atypical haemolytic-uremic syndrome (ORPHA 544472) in children. Atypical haemolytic-uremic syndrome (aHUS) is defined by a triad: haemolytic anaemia, thrombocytopenia and acute kidney injury in pediatric and adult patients. The OMIM catalogue presents the phenotypic series of aHUS with mutations of the C3, CFB, CFH, CFHR1, CFHR3, DGKE, MCP, THBD genes. Atypical haemolytic-uremic syndrome is often associated with gene mutations in proteins and activators that regulate complement. We report the case of a girl who had a manifestation of aHUS at 8 years 5 months of age and a severe relapse at 8 years 10 months of age. The relapse was characterised by manifestations of haemolytic anaemia, thrombocytopenia, acute renal damage, severe arterial hypertension, high lactate dehydrogenase and membrane attack complex levels and low C3 component. After 5 courses of haemodialysis, 3 haemodiafiltration, diuresis increased and biochemical parameters improved. We presented with ASUS in a child associated with a p.Cys1101Tyr C3 gene mutation. We used a complement inhibitor, Elizaria®, a biosimilar to the original drug eculizumab, to treat a child with atypical haemolytic-uremic syndrome due to the C3 gene mutation. The complement system inhibitor therapy with Elizaria preserved the health and life of a sick girl with a severe relapse of aHUS.

   The risk of acute kidney injury (AKI) in cancer patients is much higher than in the general population. Common causes of AKI in this group of patients are toxicity of chemotherapy com ponents and water-electrolyte imbalances. The risks of AKI increase significantly if the patient has a history of chronic kidney disease of any etiology. Risk assessment and correction, prevention and treatment of acute and chronic renal dysfunction are the standard tasks of onconephrology The clinical case of acute kidney disease described here illustrates the main mechanisms and factors of organ dysfunction and its outcomes as a con­ sequence of colorectal cancer treatment. The necessity of multidisciplinary cooperation in determining the management and treatm ent tactics of such patients is shown, that is essential for the long-term prognosis.

   The concept of focal segmental glomerulosclerosis in clinical practice is used to describe both a separate disease and morphological characteristics of secondary kidney damage. Most often, focal segmental glomerulosclerosis occurs as a result of the course of primary glomerulonephritis and is the cause of the development of nephrotic syndrome. A feature of the course of nephrotic syndrome in focal segmental glomerulosclerosis is a longer response to steroid therapy, or the formation of dependence/resistance to glucocorticosteroids. Despite the development of scientific progress, the problem of focal segmental glomerulosclerosis in primary glomerulonephritis is still relevant. Understanding the mechanisms of podocyte damage and disease progression is important not only for basic research, but also for everyday clinical practice.