The occurrence of AKI after Unilateral Nephrectomy is a situation that cannot be ignored. We considered that the occurrence of AKI will cause many adverse consequences, so we conducted this study.
In this study, we assessed the incidence of AKI following Unilateral Nephrectomy and found that AKI developed in 41.2% of our study patients. Univariate analysis revealed that gender, overweight, preoperative renal function, and Laparoscopic surgery were significantly associated with AKI. Multivariate analysis revealed that male gender, overweight, and normal preoperative eGFR were independent risk factors for postoperative AKI. Although the surgeries of urothelial carcinoma and renal carcinoma vary in terms of the procedure and scope of excision. The scope of urothelial carcinoma includes the kidney, the entire ureter, and part of the bladder. The removal of one kidney is the most important effect on the body (16, 17), so we believe that they can be combined for analysis and comparison.
Recently, a study proposed that AKI is a frequent complication after radical nephrectomy, with an incidence of up to 53.9%, and is associated with the development of CKD (18). Older age, male gender, higher BMI, and higher preoperative GFR were identified as independent risk factors for postoperative AKI (9). Although age was not significantly associated with AKI in our study (P = 0.312), the other factors were in good accordance with the results observed in our study.
These findings have a possible explanation. First, as there is a given number of nephrons for the same patient, obesity places greater strain on the kidneys leading overweight patients to develop AKI more commonly (19). Similarly, as men have a stronger metabolic capacity than women, the kidney load is also greater, so they are more likely to develop AKI. However, we reported that patients with normal preoperative renal function showed an increased risk of postoperative AKI. Surprised by the effect that preoperative renal function had on the occurrence rate of AKI,We took further analysis(Fig. 1–4). We found differences in preoperative renal function between different etiologies. And we found an interesting phenomenon that the higher the probability of CKD, the lower the probability of AKI.Therefore, we further studied the relationship between different etiologies and postoperative AKI(Table 3).
We believe that this question is interesting and warrants further investigation. In this study, the incidence of AKI was lowest in patients with non-functional kidneys and highest in those who received kidney donation. As it has been shown that the contralateral kidney undergoes compensatory hypertrophy after Unilateral nephrectomy, we made several hypotheses (2). The renal function of diseased kidneys in patients with non-functional kidneys declined gradually owing to their ability to contribute to compensatory growth processes in the contralateral kidney. Consequently, the opposite kidney adapted to the body’s needs, leading to a lower probability of AKI after contralateral Unilateral Nephrectomy. However, the kidney function of donors is normal, and the contralateral kidney cannot compensate in time after sudden loss of a kidney; therefore, the probability of AKI is higher after performing a contralateral Unilateral Nephrectomy.
Because the renal function of patients before and after surgery was inconsistent, we next conducted a comparative analysis. In some patients, renal function will increase after surgery, mainly in patients with non-functional kidneys. Patients with non-function kidneys have undergone a prolonged contralateral renal compensation before surgery; therefore, we believe that preoperative compensation of the contralateral kidney is an important factor affecting the occurrence of postoperative AKI (Fig. 1).
Figure 1. Preaopreative and postoperative creatinine ratios
Patients who had ureter tumours had a lower probability of AKI than patients with renal carcinoma, but a higher probability than patients with non-function kidneys. Therefore, we believe that the diseased kidney in patients with ureter tumours exhibits hydronephrosis to some extent, leading to compensatory growth of the contralateral kidney. However, the tumours are usually expansive and outward growing in patients with renal carcinoma, which is less damaging to kidney function (20). In our study, preoperative renal function decreased in 60.3% of patients with ureteral tumours, but in only 36.8% of those with renal carcinoma. However, the data collection and analysis of the patients with kidney cancer in this study were insufficient, and the tumour size, pathological diagnosis of the tumour, tumour grade, and affected renal function are also required. Therefore, further studies are needed to test the proposed hypothesis.
Taken together, the occurrence of postoperative AKI was closely related to the residual renal function of the affected kidney before surgery, and certain compensatory changes in the contralateral kidney before surgery were closely related to the occurrence of postoperative AKI. For patients undergoing Unilateral nephrectomy, it would be a predictor of postoperative AKI occurrence. This strategy could be employed to develop novel therapies for the prevention of AKI. Patients undergoing upper urinary tract urothelial carcinoma and some patients with advanced renal cells will require postoperative adjuvant therapy(21) Renal function is an important index in postoperative adjuvant therapy(22, 23) After hospital admission, early prediction of AKI can provide an opportunity to prevent patients from developing AKI and to determine appropriate interventions, if any, which may benefit the recovery of renal function.
Figure2. Preopreative eGFR
Figure 3. Preoperative Chi-square test of renal function for different etiologies
Figure 4. The probability of AKI occurrence in different etiologies
We used the KDIGO criteria to define AKI, this can be judged by the change in blood creatinine value, as well as by monitoring the urine volume of patients 6–24 h after surgery. However, in retrospective studies and in clinical practice, the urine volume at 6 and 12 h is often difficult to obtain; thus, no urine volume criteria were used for the definition of AKI in the present study, which makes it difficult to draw definitive conclusions.