[Clinical significance of serum and urinary biomarkers for water-salt metabolism in patients with proteinuric forms of chronic glomerulonephritis].

AIM: To determine the nature and magnitude of changes in the detectable serum and urinary biomarkers of water-salt metabolism in patients with proteinuric forms of chronic glomerulonephritis (CGN), their importance for assessing the activity and prognosis of the disease.

SUBJECTS AND METHODS: Forty-seven patients with CGN were examined. Group 1 included 10 patients with nephrotic syndrome (NS) and decreased renal function; Group 2 comprised 16 patients with persistent NS and normal renal function; Group 3 consisted of 10 patients with partial remission of NS; Group 4 included 11 patients with active hematuric CGN. A control group consisted of 9 healthy individuals matched for gender and age with the patients with CGN. The serum level of copeptin and the urinary excretion of aquaporine-2 (AQP-2) and kidney injury molecule-1 (KIM-1) were determined by indirect enzyme-linked immunosorbent assay (ELISA).

RESULTS: In the NS patients with and without renal dysfunction, the serum copeptin concentration was significantly higher than that in those with partial remission of NS or hematuric CGN and in the controls. In the patients with hematuric CGN, this indicator was virtually different from that in the control group. Urinary AQP-2 excretion was significantly similar in 3 NS groups. In the patients with hematuric CGN, the urinary AQP-2 concentration was higher than that in those with NS, but it was significantly lower than in the control group. The highest urinary excretion of KIM-1 was found in the patients with NS and diminished renal function while its excretion was significantly lower in the patients with NS and stable renal function, as in those with partial remission of NS. The lowest values were seen in the patients with hematuric CGN and in the control group; the differences between these groups were statistically insignificant. Correlation analysis showed that there was an inverse correlation between serum copeptin and urinary AQP-2 levels and between urinary AQP- 2 and KIM-1 levels.

CONCLUSION: Serum copeptin levels and urinary AQP-2 secretion may be used to assess the activity of CGN and NS and to evaluate therapeutic effectiveness. The determination of urinary KIM-1 excretion may be of the same practical value in patients with NS. It has been shown that the concentrations of copeptin, APQ-2, and KIM-1 may be used as a differential diagnostic criterion for hematuric CGN.