Dynamics of kidney disorders in children with juvenile idiopathic arthritis taking into account therapy resume

Introduction. In the study of the course and consequences of rheumatic diseases much attention is paid to comorbid conditions that significantly affect the function of internal organs, including kidneys. According to the concept of cardiorenal ratios, even minor renal impairment can be an independent risk factor for cardiovascular events and death. Objective. To determine the features of functional disorders of the kidneys in children and adolescents with juvenile idiopathic arthritis (JIA), taking into account the nature of the disease and therapy. Materials and methods. 85 children (8–18 years) with JIA, oligo- (61.5 %) and polyarthritis (38.5 %), 63 girls and 22 boys were examined. The average duration of the disease was 84.13 ± 6.28 months. The study was conducted twice with an interval of one year. Determination of renal status included studies of urinary sediment, concentration and nitrogen excretion capacity of the kidneys (fluctuations in specific weight during the day, daily proteinuria, creatinine and urea in the blood, glomerular filtration rate (GFR)). Statistical processing of the material was performed using parametric (Student's t-test (p), Fisher's angular transformation) and non-parametric parameters (Wilcoxon-Mann-Whitney), correlation and regression analysis. Results. Changes in renal function did not depend on the sex of patients and included proteinuria (9.09 %), namely microalbuminuria, which occurred in all variants of arthritis; reduction of GFR (8.26 %) – only in polyarthritis and uveitis-associated variants. Comparison of the frequency of renal changes in patients with varying degrees of disease activity showed their absence in the inactive stage of JIA. With active inflammatory process functional disorders of the kidneys occurred from 16.67 % to 26.32 % of cases, regardless of the degree of activity One year later there are positive changes: increased glomerular filtration rate (p ≤ 0.05), a tendency to decrease serum creatinine (p ≤ 0.1) on the background of basic methotrexate therapy up to 15 mg/m2/week. The combination of methotrexate therapy with the anti-TNF immunobiological drug (adalimumab) showed greater efficacy in improving renal function, a significant increase in GFR (p ≤ 0.05), a decrease in serum creatinine (p ≤ 0.05) and proteinuria (р ≤ 0,05). Conclusions. Children with JIA have changes in renal function, more often with uveitis-associated arthritis and methotrexate over 15 mg/m2/week. The inclusion of immunobiological drugs in the treatment not only reduces the activity of the disease, but also reduces the risk of concomitant comorbid lesions of internal organs, including kidneys.