Additional diagnostic capabilities of water-salt loadings in patients with chronic kidney disease stage І–ІІІ

Abstract

Background. The number of patients with chronic kidney disease (CKD) increases every year, including those requiring renal replacement therapy. According the Kidney Disease Improving Global Outcomes guidelines, we use the category of albuminuria and estimated glomerular filtration rate (eGFR) to assess the CKD prognosis, but there are many researchers searching for new diagnostic markers for early detection of CKD progression. It would be interesting to use for this aim such an available indicator as uric acid. So, the objective was to assess the changes in serum uric acid level in patients with CKD stage I–III after water-salt loading of 0.5% sodium chloride at a rate of 0.5% of body weight, and to identify the relationship of this indicator with a decrease in eGFR after one year. Materials and methods. The study included 102 patients with CKD stage I–III. We used the renal functional reserve test proposed by A.I. Hozhenko, adapted to ambulatory medical care services with measuring serum uric acid level before and after water-salt loading with 0.5% sodium chloride. Results. During the year of observation, patients whose serum uric acid level increased after water-salt loading, or remained the same, or decreased by less than 5 mmol/l had a statistically greater decrease in the glomerular filtration rate: 9.2 ± 10.7 ml/min/1.73 m² in comparison with patients who had a decrease in uric acid level of more than 5 mmol/l after water-salt loading: 4.1 ± 10.0 ml/min/1.73 m². Conclusions. When expanding the capabilities of the renal functional reserve test by determining the change in uric acid level, we can individualize the patient’s prognosis in terms of eGFR decline.