FUNCTIONAL STATE OF RENAL PARENCHYMA IN CHILDREN WITH DYSMETABOLIC NEPHROPATHY

Abstract. Metabolic nephropathy in children is a relevant issue in our time, as the prevalence of this disease is increasing. Negative consequences of metabolic nephropathy include a gradual deterioration of kidney function. A significant aspect is the fact that metabolic nephropathy can lead to the development of chronic kidney disease in children. Chronicity requires continuous medical monitoring and treatment to support kidney function and prevent further complications, such as renal insufficiency and other metabolic disorders. There is no doubt that one of the leading pathogenetic factors in kidney dysfunction is hypoxia. It can be caused by both hemodynamic disturbances associated with renal pathology and tissue respiration disorders in congenital dysplasia of the kidney's connective tissue, which arises in the embryo under the influence of epigenetic factors in utero and is further exacerbated by various epigenetic factors in postnatal life. Purpose of the work to investigate the functional state of kidney parenchyma in children with dysmetabolic nephropathy. Materials and methods. Two groups of children were examined: those with a complicated course of dysmetabolic nephropathy, a history of inflammatory episodes of the urinary system organs (Group I - UN, 52 children), and dysmetabolic nephropathy with persistent crystalluria (Group II - DN, 56 children). A control group consisted of 65 healthy children. Tubular reabsorption, as a partial function of the proximal segment of the nephrons, was assessed based on urinolysis test data, specifically the levels of excretion of inorganic phosphates, proteinuria, amino acids, reduced sugars (maltose, sucrose, fructose by Benedict's test), glucose (by Gaines's test), and calcium (by Sulcovitch's test). The level of creatinine and glycosaminoglycan (GAG) excretion in daily urine in children with dysmetabolic nephropathy was determined and compared with data from healthy children in the control group. Research results. In children from both observation groups, a significantly high frequency of hyperphosphaturia (94.23% and 96.42%), calciuria (94.23% and 89.28%), glucosuria (78.85% and 73.21%), increased excretion of amino acids in the urine (40.38% and 37.5%), microproteinuria (32.69% and 28.57%), and increased excretion of reduced sugars (28.85% and 26.79%) were observed. The daily excretion of creatinine, glycosaminoglycans, and oxypyrrolidine in the urine of children with dysmetabolic nephropathy indicates a significantly reduced level of creatinine in the daily urine in the majority of children in Group I (0.56±0.19 g/L, 80.77% of those examined) and more than half of the children in Group II (0.83±0.08 g/L, 57.14% of those examined), compared to the data from healthy children in the control group (1.25±0.75 g/L, 0.0%). Conclusions. The analysis of the functional state of the kidney tissue in oxalate dysmetabolic nephropathy in children allows us to testify to the presence of tubular and glomerular partial renal tissue failure. Significant decreases in creatinine excretion and increased excretion of glycosoaminoglycans in the urine and significantly higher levels of oxyproline in the urine indicate the presence of glomerular type partial renal failure in oxalate dysmetabolic nephropathy in children and the presence of undifferentiated dysplasia of the renal connective tissue with the onset of its sclerosis with subsequent transition to interstitial nephritis. The presence of these changes in the vast majority of children with complicated course of oxalate dysmetabolic nephropathy in the period of clinical and laboratory remission of the inflammatory process indicates the priority of renal connective tissue dysplasia and paucity of renal failure in the pathogenesis of dysmetabolic nephropathy and its severity in children. Indicators of oxyproline creatinine, glycosoaminoglycans and oxyproline excretion can be used as epigenetic markers of susceptibility to dysmetabolic nephropathy in general and its more severe course in particular. Keywords: dysmetabolic nephropathy, functional state, kidney parenchyma, nephron.