# Evaluation of Chronic Kidney Disease Risk Factors after Radical Nephrectomy
## 4 Discussion
RN of high-volume tumors is one of the most difficult surgical procedures performed in urology because of high intraoperative blood loss [33]. Even when RN is performed by a highly skilled urologist, there is still the opportunity for excess blood loss. The open operative approach, Neves classification IV level of renal thrombus extension and resection of IVC are independently associated with increased blood loss during RN [34]. While there are not a lot of prospective studies on the impact of intraoperative blood loss on postoperative CKD after RN, studies have shown that perioperative blood loss of over 250 mL during open PN might be associated with the risk of postoperative GFR decrease by over 25%. The risk increases by 0.1% for every mL of blood loss (OR = 1.001; \(p\) = 0.05) [35]. In a study by [PERSON] et al., blood loss requiring blood transfusions during PN is related with a three-fold chance of CKD (HR = 2.96; \(p\) < 0.0001) [18]. In large tumors (>7 cm), the estimated blood loss and risk for complications is higher for kidney resection than RN (\(p\) < 0.001) [36]. In our study, loss of blood was assessed by measuring the amount of blood in the pump tank and the weight of the surgical dressing. It was evident that each 1 mL of estimated blood loss during RN was allied with a higher incidence of CKD (OR = 1.01, \(p\) < 0.001). Multiple studies have shown that growing RCC reduces the mass of renal parenchyma and induces an increase in the parenchymal volume of the contralateral kidney. This process is known as compensatory hypertrophy and is more apparent in larger tumors (>7 cm) [37]. Studies using multivariate analysis have shown that higher preoperative contralateral kidney volume is associated with better postoperative RF outcomes (OR = 0.98, CI 0.96-0.99, \(p\) < 0.001) [38]. Before surgery, kidney volume is associated with postoperative eGFR in PN as well as in RN patients (\(p\) < 0.001) [28; 37]. [PERSON] with colleagues found that sCr clearance < 60 mL/min after kidney surgery can be predicted by a remnant parenchymal volume of 170 mL, data sensitivity of 0.59 and specificity of 0.74 [30]. MetS can negatively influence the perioperative outcome after RN. MetS is a type of anabolism and catabolism disorder, including visceral overweight, HTN, dyslipidemia and hyperglycemia associated with increased morbidity. A study of [PERSON] et al. presented that oncological patients with MetS demonstrated a much lower recovery rate after RN as well as an increased risk for progressing renal insufficiency. Patients with MetS were more likely to have a lower CKD class 2 years after RN than patients without MetS (OR 4.28; \(p\) = 0.017) [39]. It is important to note that MetS is prevalent in RCC patients and is correlated with worse survival rates without disease progression than in patients without MetS (HR = 1.98; \(p\) = 0.04) [40]. Our univariate analysis showed that patients without MetS were at increased risk for postoperative CKD (OR = 0.27, CI 0.11-0.62, \(p\) = 0.003); however, the adjusted multivariable test did not find any difference between MetS and non-MetS participants in postoperative CKD group. The impact of the independent effect of MetS components on RF after RN has been poorly investigated. Isolated increased BMI is common in patients with RCC and requires a more careful surgical approach as it is associated with an increased operating time (OR = 1.174; \(p\) = 0.030) and greater loss of blood (\(p\) = 0.017) during laparoscopic and open RN [41]. However, another study found that increased BMI alone is not associated with intraoperative and postoperative complications (\(p\) = 0.790) so it need not be regarded as a contraindication for RN [42]. The ratio of neutrophil-to-lymphocyte is a novel marker for inflammation detection and is estimated from complete blood count and used as a prognostic indicator for progression of CKD. High NLR correlates with high CRP and is associated with chronic inflammation and inflammatory processes in glomerula.