Introduction. Despite the development of minimally invasive technological methods for the treatment of urolithiasis, improving the functional state of the kidneys in the postoperative period does not lose its importance at the present time. The decrease and loss of renal function after surgical treatment of complex forms of nephrolithiasis in various ways creates the problem of choosing one or another surgical technique in order to avoid negative results of surgical treatment. modern urology. Purpose of the work: to assess the correlation between the volume of intraoperative blood loss and dynamic changes in glomerular filtration rate (GFR) in the postoperative period with various methods of surgical treatment of large and complex kidney stones. Purpose: to assess the correlation between the volume of intraoperative blood loss and dynamic changes in the GFR in the postoperative period with various methods of surgical treatment of large and complex kidney stones.

Materials and methods. The study selected data from 97 patients with urolithiasis, large and complex kidney stones of the urological department of the city hospital No 2 of the city of Nur-Sultan of the Republic of Kazakhstan. The median age was 52 (23–73) years. The average area of a kidney stone was 428.3±36.1 mm², its average density according to Hounsfield was 1042.9±34.8 HU. All patients were divided into 3 cohort comparison groups according to the method of surgical treatment: percutaneous nephrolithotripsy (PCNL) on prone position (1 group) – 44 patients (45.4%), PCNL on the supine position (2 group) – 29 patients (29.9%), laparoscopic pyelolithotomy (3 group)– 24 patients (24.7%). The median baseline GFR in the 1 group was 91 ml/min/1.73 m², in the 2 group 95 ml/min/1.73 m², in the 3 group 101 ml/min/1.73 m². The average duration of surgical intervention for 1 group was 92.8±6.8 min, for 2 group – 119.6±10.9 min, for 3 group-146.9 ± 6.1 min. The mean blood loss in 1 group was 144.5±9.1 ml, in 2 group 235.3±19.1 ml, in 3 group 43.1±5.2 ml.

Results. A decrease in GFR below 60 (ml/min/1.73 m²), corresponding to stage III of chronic kidney disease (CKD), was most pronounced in the 2 group: from 3 (3.1%) cases before surgery to 7 (7.2%) cases in postoperative period. A decrease in GFR below 30 (ml/min/1.73 m²), which corresponds to stage IV CKD, also had negative dynamics in the group of patients with 2 group: from 2 (2.1%) to 3 (3.1%) cases respectively. In the rest of the studied groups, there was no negative dynamics of GFR. A correlation was found between GFR in the postoperative period and intraoperative blood loss (r = 0.410, p<0.001).

Conclusions. Surgical treatment of urolithiasis of the kidneys is associated with risks of intraoperative blood loss, the volume of which directly correlates with the deterioration of the functional state of the kidneys in the postoperative period. Reducing the volume of intraoperative blood loss in various surgical methods for the treatment of urolithiasis helps to minimize the risk of developing acute kidney injury in the postoperative period.