SUMMARY
Aim of the research: to establish the role of undifferentiated connective tissue dysplasia, as a manifestation of violation of fibrillogenesis, in the severity of the course of pyelonephritis in children.154 children with pyelonephritis from 3 to 18 years were examined. As a result of catamnestic surveillance, they were divided into 2 groups: I – 92 persons, children with chronic pyelonephritis in which were diagnosed 3 or more episodes of relapse of pyelonephritis during the year, and II – 56 children with acute pyelonephritis, in which during the year no relapses were noted. The control group were 65 somatically healthy children of the same age (III - health-control). All children had a routine comprehensive clinical and laboratory examination and clinical and laboratory markers of a fibrillogenic disorder were established.In children with chronic pyelonephritis, the frequency of all analyzed complaints was significantly higher than in children with acute pyelonephritis without relapses: frequent headaches – 56.52 % versus 25.0 %, appetite loss – 28.26 % vs. 19.64 %, frequent abdominal pain – 52.17 % vr. 32.14 %, increased fatigue – 41.30 % vr. 28.57 %.In children with chronic pyelonephritis, phenotypic signs of undifferentiated connective tissue dysplasia (UCTD) were significantly more marked, such as joint hypermobility (in 52.0 % of children versus 5.4 %), asthenic body structure (59.0 % vs. 26.78 %), visual disturbance (84.8 % vs. 32.14 %), chest deformity (42.4 % vs. 8.9 %), scoliosis (52.17 % vs 10.7 %), arachnodactyly and predisposition to bleeding were observed only in children of the 1st group (22.5 % and 4.34 % respectively).In practically all children with chronic pyelonephritis, the values of free and bound oxyproline fractions in blood plasma were significantly increased (47.14±0.03 µmol/l and 40.08±0.03 µmol/l, respectively), according to arithmetic meanings, reliably differing from the data of children with acute pyelonephritis (17.65±0.01 µmol/l and 17.22±0.02 µmol/l), in which these oxyproline fractions were elevated only in 12.0 % and 16.0 % of the subjects.In 97.0 % of children with chronic pyelonephritis, the level of oxyproline in urine was elevated and significantly exceeded the level of excretion of oxyproline in urine in children with acute pyelonephritis.The presence of UCTD in a child plays an important role in the process of chronic pyelonephritis, and children with its manifestations have a heavier course of disease with frequent relapses, therefore, the presence of signs UCTD is prognostically unsuccessful, which dictates the need for the appointment of metabolic therapy in the first episodes of the disease in children, if they have clinical and laboratory manifestations of UCTD.