Violation of reserve filtration capacity of kidneys in patients with early rheumatoid arthritis

Objective: to investigate the reserve filtration capacity of the kidneys in patients with rheumatoid arthritis onset as a potential marker of subclinical renal dysfunction. Materials and methods. 47 patients over the age of 18 years with early rheumatoid arthritis (eRA) were included into this study (duration of symptoms of the disease is no more than 12 months). The average age of patients was 50.71 ± 2.25 years (from 18 to 76 years), 80% of them were women, the average duration of the disease at the time of the initial study was 9.21 ± 0.43 months. Results. When we were determining the functional renal reserve (FRR) by evaluating the increase in the glomerular filtration rate (GFR) after the oral loading test, a statistically significant change was noted in the group of patients with eRA in FRR in comparison with the control group – 34,6% in comparison with practically healthy persons, while basal GFR Cockroft-Gault in these groups did not differ significantly. Among the general population of patients with eRA, the preserved FRR was noted in a third of cases (32%), in other cases, a certain degree of its decrease was recorded. A similar dynamics, differing only in the magnitude of differences, was observed for albumin-creatinine ratio – A / C urine: overall, in eRA patients, it was 6.3 times higher in comparison with practically healthy persons. The prevalence of patients with microalbuminuria for the group with the eRA was about 38%. Conclusion. In patients with eRA, already in the onset of the disease, there is a disruption of the functional status of the kidneys, which manifests itself in the worsening of reserve glomerular filtration: EDF in eRA was 34.6% lower than in practically healthy individuals, and the number of patients with impaired FPR was significantly higher than in the control group (χ2 = 13.79, p <0.01). The Pearson correlation analysis (r = -0.57, p