Brain natriuretic peptide and catecholamines in adolescents with juvenile idiopathic arthritis

Abstract

Juvenile idiopathic arthritis is a group of chronic diseases of uncertain etiology, in which an immuno­inflammatory process develops with systemic damage to the vascular endothelium, leading to the involvement of vital organs and systems against the background of persistence of the inflammatory process. Objective — to determine the level of excretion of catecholamines in the daily urine and natriuretic peptide in the blood of adolescents with juvenile idiopathic arthritis. Materials and methods. The study involved 56 patients with juvenile idiopathic arthritis, aged (13.28 ± 0.38) years, including 17 boys, 39 girls. The polyarticular form of the disease was diagnosed in 48 patients (86 %), the oligoarticular form was in 8 (14 % of patients). The duration of the disease was (68.96 ± 6.29) months (from 12 to 180 months). All patients received methotrexate for more than 12 months, the average dose of which was (11.73 ± 0.39) mg/m2 per week. The control group consisted of 46 (27 boys and 19 girls) practically healthy peers (14.72 ± 0.28) years. The content of catecholamines (adrenaline and norepinephrine) in daily urine was studied by iodine oxidation with the formation of fluorescent trihydroxyindoles (adrenolutin and norepinephrine) and subsequent fluorimetry, as well as the level of brain natriuretic peptide in the blood by competitive immunoassay. Results and discussions. In patients with juvenile idiopathic arthritis, the level of excretion of catecholamines in the daily urine remains within the age norms, but significantly lower than in healthy peers (p < 0.01), the adrenaline/norepinephrine ratio also decreases (p < 0.05). A significant increase in the level of brain natriuretic peptide in the blood was found in patients with juvenile idiopathic arthritis (p < 0.01), especially in children aged 11—14 years and disease duration up to 5 years (p < 0.05). Conclusions. The change in the ratio of catecholamine excretion and blood natriuretic peptide level determines the processes of formation of morphofunctional disorders of the cardiovascular system in children with juvenile idiopathic arthritis.