The hemolytic-uremic syndrome is a serious problem in pediatrics and pediatric nephrology. Given the progressive course of the hemolytic-uremic syndrome up to the terminal stage of renal failure, it is necessary to search for markers of damage to the renal tissue as prognostically significant factors in the development of nephrosclerosis. This is of particular importance in childhood to optimize the management of patients with hemolytic-uremic syndrome. Disturbance of serotonin metabolism by damaged endothelial cells is associated with a progressive decline in kidney function and nephrosclerosis development, and is a predictor of an unfavorable development of chronic kidney disease. It has been established that the degree of kidney damage is demonstrated by indicators of the catecholamine metabolism activity and their ratio, reflecting a disturbance of the kidneys filtration capacity.