Aim. To determine the effect of standard treatment on changes in the structural and functional properties of erythrocytes in obstructive and non-obstructive acute pyelonephritis.
Materials and methods. The structural and functional properties of erythrocytes and their intracellular metabolism in 78 patients with a diagnosis of primary non-obstructive and secondary obstructive acute pyelonephritis, randomized by age, gender, and the minimum number of concomitant diseases were investigated.
Results and discussion. In acute non-obstructive pyelonephritis, changes of the content of proteins in circulating erythrocytes responsible for the structure formation and stabilization of the plasma membrane (α-spectrin, anion transport protein, pallidin, protein 4.1), intracellular metabolism (anion transport protein, glutathione-S-transferase), membrane flexibility and shape (actin, tropomyosin) are insignificant, alike from acute obstructive pyelonephritis. In addition, processes of lipid peroxidation inside red blood cells are intensified, and oxidative stress develops with a decrease in the sorption capacity of erythrocytes, as well as the content and ratio of lipid fractions in the plasma membrane, which form the basis of the lipid components and play the main role in the sequencing of protein macromolecules and the normal metabolism of red blood cells.
Conclusion. In acute obstructive pyelonephritis, changes in the content and ratio of proteins and lipids in the erythrocyte membrane lead to functional rearrangements that are not corrected by standard treatment.

Keywords: structural and functional properties of red blood cells, non-obstructive and obstructive acute pyelonephritis