|Year : 2015 | Volume
| Issue : 2 | Page : 238-242
|Comparison of renal function following donor nephrectomy versus radical nephrectomy for renal tumor
Mohamed Etafy1, Fatma Saleh2, MA Abdel Aal2, Maher Gawish2, Gamal Morsy2
1 Jackson South Hospital, Miami, FL, USA
2 Alazhar Faculty of Medicine, Cairo, Egypt
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|Date of Web Publication||3-Mar-2015|
| Abstract|| |
In this study, we compared renal function in patients after donor nephrectomy (DN) and radical nephrectomy (RN). We retrospectively reviewed 68 patients (mean follow-up 15 months), including 30 patients who had undergone DN and 38 patients who had undergone RN. The study was performed between April 2006 and July 2010 at a single institute. Patients were matched for age and co-morbidities (hypertension and diabetes mellitus). We calculated the estimated glomerular filtration rate (eGFR) using the Modification of Diet in Renal Disease study group equation. Parameters studied included GFR (≥60 to <60 mL/min/1.73 m 2 ), serum creatinine (>2.0 mg/dL), metabolic acidosis (serum bicarbonate <22 mmol/L) and proteinuria (>30 mg). There were no significant demographic differences between the two study groups. After a mean follow-up of 15 months, low eGFR (<60 mL/min/1.73 m 2 ) was seen in 28% and 6.7% of patients in the RN and DN groups, respectively (P = 0.03). Similarly, proteinuria was seen in 21% vs 0%, P = 0.007, and de novo elevated creatinine was seen in 13% vs 0%, respectively P = 0.04; thus the changes were greater in the RN group. Our study shows that undergoing RN had a significantly greater risk of developing renal insufficiency and proteinuria compared with age-and co-morbidity-matched patients undergoing DN. We concluded that patients undergoing RN show a significantly greater risk of developing renal insufficiency and proteinuria compared with the patients undergoing DN.
|How to cite this article:|
Etafy M, Saleh F, Abdel Aal M A, Gawish M, Morsy G. Comparison of renal function following donor nephrectomy versus radical nephrectomy for renal tumor. Saudi J Kidney Dis Transpl 2015;26:238-42
|How to cite this URL:|
Etafy M, Saleh F, Abdel Aal M A, Gawish M, Morsy G. Comparison of renal function following donor nephrectomy versus radical nephrectomy for renal tumor. Saudi J Kidney Dis Transpl [serial online] 2015 [cited 2019 Jan 18];26:238-42. Available from: http://www.sjkdt.org/text.asp?2015/26/2/238/152401
| Introduction|| |
The surgical removal of one kidney results in compensatory changes in the contralateral kidney within the first few months.  Patients who have a healthy kidney removed for donation can be expected to have normal function in their remaining kidney and can be expected to have the same life expectancy as a subject in the general population who has not had a kidney removed.  If the kidney was removed due to renal cell carcinoma, the contralateral kidney might have been affected by other previous factors caused by the tumor, which might affect life expectancy.
Radical nephrectomy (RN) was the principal form of managing cortical renal masses, which changed with better understanding of tumor biology and advances in radiographic imaging. Thus, nephron-sparing techniques are frequently used now. 
RN carries the risk of causing chronic renal insufficiency (CRI), which in turn results in a substantially higher risk of hospitalization (10%), cardiovascular events (40%) and death (20%). ,,
Additionally, RN predisposes to metabolic derangements, as the normally functioning parenchyma is also excised.  Diminished renal functional capacity might lead to retention of renal acid load, contributing to metabolic acidosis (MA), which is further aggravated by a reduction in new renal bicarbonate generation coupled with possible decreases in bicarbonate absorption. 
Early studies on donor nephrectomy (DN) from transplant centers have revealed that in the short term, kidney function recovers to 70% of pre-donation glomerular filtration rate (GFR)  and that there is no accelerated loss of kidney function among donors.  Moreover, the incidence of end-stage renal disease (ESRD) is typically found to be between 0.2% and 0.6% among large donor populations, which is comparable to that of the general population. ,
| Aim of the Study|| |
With this study, we hope to determine whether there is a difference between patients who undergo DN or RN with regard to long-term renal function. We also intend to examine the risk factors for renal dysfunction in these two patient groups. The results will enable us to predict which patients are more likely to develop renal insufficiency post-operatively and to advise such patients accordingly.
| Patients and Methods|| |
In a retrospective study, we reviewed 68 patients who had undergone DN (n = 30) or RN (n = 38) between April 2006 and July 2010 at our institution. Patients were matched for age and co-morbidities [hypertension and diabetes mellitus (DM)]. We made a two-matched group by applying these exclusion criteria.
Exclusion criteria for patients included the following:
- Pre-operative renal insufficiency.
- Pre-operative or post-operative metastasis.
- Co-morbidity (hypertension, DM, heart diseases and other tumors).
- Age >60 years.
- Solitary kidney.
The primary end-point was the occurrence of CRI, defined as an estimated GFR (eGFR) of <60 mL/min/1.73 m . The secondary end-points included the development of a creatinine level of ≥2.0 mg/dL (high), MA (serum HCO3- of <22 mmol/L) and proteinuria (urine showing >30 mg protein). The eGFR was calculated using the Modification of Diet in Renal Disease (MDRD) Study Group equation.  Demographics including age, sex, race, body mass index (BMI) and smoking; disease characteristics (stage, pathology); outcomes, i.e. low eGFR, high serum creatinine level, MA and proteinuria, and their time to development, were recorded. We used the 2002 TNM stage classification system. 
Follow-up was undertaken post-operatively at 1, 3, 6 and 12 months and then yearly.
The results were analyzed statistically to check whether there is a significant difference in developing low eGFR, high serum creatinine, MA or proteinuria after RN or DN.
Descriptive statistics were analyzed based on whether patients underwent RN or DN. Means were compared between the groups (RN vs DN) using Fisher's test and chi-squared tests for variables, with P <0.05 considered to indicate statistical significance.
| Results|| |
Thirty-eight patients underwent RN and 30 patients underwent DN, and the mean follow-up was 18 months. The demographic features of the study patients are shown in [Table 1].
There were no significant pre-operative differences between the RN and DN groups in the proportion of patients with proteinuria, low eGFR and MA. However after surgery, a significantly greater proportion of patients in the RN group had low eGFR (28% vs and 6.7%, P = 0.04), proteinuria (21% vs 0%, P = 0.009) and MA (25 % vs 6%, P = 0.001), and developed de novo high serum creatinine (11% vs 0%, P = 0.04) [Table 2].
| Discussion|| |
Among patients with a normal pre-operative serum creatinine level and a normal contralateral kidney, RN is a significant risk factor for developing new-onset CRI. ,, Although the risk of progression to ESRD and dialysis-dependence might be low in such patients,  other complications of CRI including hypertension, anemia, malnutrition, neuropathy, reduced quality of life and increased risk of cardiovascular disease and mortality might occur. ,,
In the present review of 68 well-matched patients who had undergone RN or DN, there were significant differences in the incidence of a high creatinine level and low eGFR after RN and DN [Table 1]. Both these criteria have been used as parameters indicating moderate CRI, although the National Kidney Foundation reported that actual or eGFR values are more accurate reflections of kidney function than serum creatinine level.  For the development of a high creatinine level and low eGFR, our results in the RN group were similar to previously published reports. Using the MDRD equation and an eGFR criterion of <60, Malcom et al  reported that 44.7% of patients undergoing RN developed de novo CRI. Lucas et al  reported that 21 of 36 patients (60%) undergoing RN developed de novo CRI (12%). Similarly, the Memorial-Sloan Kettering group  reported a 69% incidence (142/204) of de novo CRI (using an eGFR of <60 as the criterion) in the RN group. The incidence of new-onset CRI using an eGFR of <60 in the present analysis corroborates the increasing evidence, showing greater preserved renal function after DN than RN. We also assessed the incidence of new-onset CRI using a serum creatinine threshold of ≥ 2.0 mg/dL, similar to Lau et al. With this criterion, the Mayo group found that the 10-year incidence of CRI was significantly high in the RN group (22.4%). In the present study, there was a similar trend for the incidence of CRI (28% for RN and 6.7% for DN, P = 0.04).
Our results in patients who had undergone DN were similar to previously published studies on 3529 donors; after an average duration post-donation of six years, the mean serum creatinine was 98 μmol/L (1.11 mg/dL, range 58-119 μmol/L) and the average GFR was 86 mL/min/1.73 m 2 (range 64-117). The average decrement in GFR after donation was 26 mL/min/1.73 m (range 8-50).
The incidence of clinical proteinuria after DN or RN has also been reported. ,,,,,, The present study showed significantly higher levels of proteinuria in the RN than in the DN group (21% vs 0%, P = 0.007). Similar results regarding RN have been reported by others, who also showed worse long-term clinical outcome when patients were stratified by qualitative urine protein content. , In our study, none of the patients in the DN group developed proteinuria, which might be due to the short duration of follow-up.
The association between CRI and MA is well established, ,,, although the exact prevalence of MA in CRI is unknown. Severe CRI can lead to MA as a consequence of insufficient renal tubular bicarbonate reabsorption or abnormal bicarbonate production. The acidosis resulting from CRI is generally mild to moderate (plasma bicarbonate 12-22 mmol/L). , However, even mild degrees of acidosis can have significant adverse consequences,  including muscle-wasting, hypo-albuminemia, bone disease, impaired insulin sensitivity and abnormalities in thyroid function and basic metabolic rate. Early studies of MA in CRI have suggested that MA occurs when severe CRI develops (GFR ≈20 mL/min or less). , However, recent evidence suggests that advanced age (>60 years) and lesser degrees of CRI are also associated with the development of MA. ,, Given these associations, we hypothesized that significant degree of MA might be detectable in patients after RN.
It is striking that patients with renal tumors treated with RN had a higher incidence of MA than would be expected based on the degree of CRI. Most patients who developed de novo CRI also developed MA. More recently, a mechanism implicating MA in exacerbating declining GFR through the endothelin A receptor has been outlined, suggesting that MA actually has a substantial role in exacerbating CRI.  In our study, we found a higher occurrence of MA in the RN than in the DN group (25% vs 6%, P = 0.001). This is similar to a previous study of Malcom et al,  who reported that MA occurred in 12.8% of patients following RN.
The limitations of our study include the retrospective design, including inherent biases. The use of the abbreviated MDRD equation to estimate GFR is an additional limitation. Despite these limitations, our findings are supported by inclusion of many patients with an intermediate-term follow-up. To the best of our knowledge, this study represents the first attempt to determine whether there is a difference between DN and RN patients regarding their renal function.
| Conclusion|| |
Patients undergoing RN show a significantly greater risk of developing renal insufficiency and proteinuria compared with the patients undergoing DN.
We are aiming in this study to open the door of more research studies addressing the risk factors for morbidities after RN
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Dr. Mohamed Etafy
Jackson South Hospital, Miami, FL
[Table 1], [Table 2]
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