| Abstract|| |
The early changes that occur in the volume and function of the remaining kidney, after uni-nephrectomy for organ donation, were studied in 25 living donors. Serum creatinine (S Cr), creatinine clearance (Cr Cl), renographic clearance tests for total and split renal functions as well as renal volume using ultrasound were determined before and three months after donation. In 76% of the donors, Se Cr showed an increase after kidney donation, but all values were within normal range. The total kidney function in terms of Cr Cl, showed a drop of 36% from the pre-donation value. After three months post donation, the clearance of the remaining kidney increased by 5% to 64% (mean 34%) of the pre-donation values, measured by Tc 99m DTPA renography. Compensatory hypertrophy of the remaining kidney also occurred as evidenced by the ultrasound evaluation which showed an increase in the renal volume by 15%. Our study shows that compensatory changes occur early i.e., within the first three months after uni-nephrectomy. However, prolonged follow-up of these donors is necessary to assess the longterm structural and functional changes in the remaining kidney.
Keywords: Renal volume, Renal function, Donor nephrectomy, Living related donors.
|How to cite this article:|
Shehab AB, Shaheen FA, Fallatah A, Al-Jobori AG, Sheikh IA, Al-Koussi M. Early changes in volume and function of the remaining kidney after unilateral donor nephrectomy. Saudi J Kidney Dis Transpl 1994;5:474-8
|How to cite this URL:|
Shehab AB, Shaheen FA, Fallatah A, Al-Jobori AG, Sheikh IA, Al-Koussi M. Early changes in volume and function of the remaining kidney after unilateral donor nephrectomy. Saudi J Kidney Dis Transpl [serial online] 1994 [cited 2020 Mar 31];5:474-8. Available from: http://www.sjkdt.org/text.asp?1994/5/4/474/41139
| Introduction|| |
Living related kidney donation for renal transplantation is possible because of the fact that kidneys have a physiologic reserve capable of providing between four to five times the minimum required renal function  . During the early period of renal trans plantation, the wisdom of utilizing a kidney from a living donor was constantly debated. The perioperative and long-term risks were of concern ,, . However, with the advent of modern investigatory armamentarium and breakthrough evolution in the fields of anesthesiology and intensive care, the earlier concepts have changed. Recent reports have emphasized the fact that unilateral nephrectomy for donation is safe and is accompanied by only minimal mortality  and morbidity  . The long-term life expectancy of these donors has been reported to be almost the same as that of age-matched healthy individuals ,,,,, .
Several studies have previously investigated the impact of kidney donation on renal functions in these donors ,,,, . However, the functional and structural changes that occur in the remaining kidney of the donors continues to evoke great interest , . This study is aimed at exploring, by non-invasive techniques, the early changes in volume and function that occur in the remaining kidney after donor nephrectomy.
| Materials and Methods|| |
The study included twenty-five living related donors (LRD). There were 12 females and 13 males with a mean age of 29 years. Prior to donation, each donor was subjected to extensive series of investigations to assess the fitness for kidney donation in general and to ensure good kidney function in particular. The demographic data of the study patients are given in [Table 1].
Work-up of potential donors
Measurement of serum creatinine (S Cr) and creatinine clearance (Cr Cl) values was used to screen the potential living related donors (LRD) for the feasibility of kidney donation. Estimation of creatinine levels in serum and urine was done using 3M/Hitachi System 705 autoanalyzer following the principle of Jaffe as described by Hare  .
Technetium 99m Stannous Diethylene Triamine Penta Acetic acid (Tc-99m DTPA) renographic study was used for the estimation of total as well as split renal functions as expressed by glomerular filtration rate (GFR) of each kidney which was determined by using GE STARCAM 400A Gamma camera connected to GE computer. The GFR was calculated two to three minutes after injection of the isotope using Gates method  .
Renal ultrasound was performed recording the maximum dimensions of length, width and thickness using ULTRA MARK 4 A ultrasound system (Advanced Technology Laboratories, Inc. W. Germany). Renal volume was calculated by the formula, length x width x thickness in ml  . Three dimensional renal measurements were recorded during routine abdominal ultrsound performed to exclude any anatomical abnormalities.
The selection of the kidney for donation was based on split renographic clearance studies. A difference in GFR of less than 10 ml/min, between the two kidneys was accepted as normal variance and both kidneys were considered as having equal function  . If the difference in GFR exceeded 10 ml/min, the kidney having better function was kept for the donor (remaining kidney) and the contralateral kidney was used for donation (donated kidney).
Re-evaluation after kidney donation
The donors were reassessed, three months after kidney donation to assess the changes in renal volume and function. The following investigations were repeated, namely, S Cr, Cr Cl, renographic clearance for GFR and renal volume.
Statistical analysis was done using paired T-test.
| Results|| |
The right kidney was selected for donation in 18 out of 25 cases (72%), as shown in [Table 1]. Significant difference in GFR between the two kidneys ( > 10 ml/min) was seen in nine cases (36%). The GFR of the right kidney was less than the left in six cases [Table 2]. Equal GFR was observed in the right and the left kidneys in 16 cases, but in 12 cases (young females in their child bearing period), right kidneys were selected for donation since this kidney is usually more prone to extra-urinary compression by the gravid uterus  . The mean GFR of the donated kidney was 48 ± 6.9 ml/mm while that of the remaining kidney was 51.9 ± 5.4 ml/mm (P <0.05).
The impact of unilateral nephrectomy on the renal function and volume of the remaining kidney is illustrated in [Table 3]. Serum creatinine showed a rise in 19 of 25 donors (76%). Pre-operative mean S Cr was 0.9 ± 0.18 mg/dl and the mean S Cr three months post donation was 1.1 ± 0.18 mg/dl, a rise that was statistically significant (P<0.001). However, all the readings were still within the normal range. In all LRD, Cr Cl exhibited variable decrease. The pre-operative and follow-up mean Cr Cl levels were 109 ± 18 and 69.5 ± 11.1 ml/min respectively; a statistically significant difference (P< 0.001). Isotope renography carried out three months post operatively showed a rise of GFR in the remaining kidney ranging from 5 to 64% (mean 34%) of the pre donation value in all the donors [Table 3].
Renal volume of the remaining kidney also showed an increase in all the donors, that ranged from 7 to 45% of the pre-donation value. The mean value pre-donation was 170.7 ± 28.5 ml and post-donation was 198 ± 40.9 ml.
| Discussion|| |
There are several factors that favor living related donor kidney as a better option for renal transplantation. The long-term survival rates of both patients and grafts are better than that seen among recipients of cadaveric donor transplants , . The operation can be electively performed and properly planned. The period on dialysis can also be shortened, if donor selection is made early.
Despite these advantages some transplant centers do not encourage living related donation and may rarely or never perform such a transplant since they consider perioperative mortality and morbidity a significant limitation ,, . Najarian et al  reported five cases of perioperative mortality among 19,368 LRD uninephrectomies performed in USA between 1980 and 1991, an incidence of less than 0.04%. Bay and Hebert compiled data from 16 series and found an incidence of major complications as 1.8%  . However, survival studies published by Cosimi  indicate that the five-year life expectancy of a unilaterally nephrectomized 35 year old male donor is 99.1% as compared to 99.3% normal expectancy. Long-term follow-up studies have failed to identify a significantly increased incidence of either hypertension or impaired renal function in LRD followed-up for as long as 19 years after unilateral nephrectomy ,, .
In our study, the observed S Cr levels three months after donation were still within the normal range in all the donors, in spite of showing a statistically significant rise in 76% of the study subjects. Similar findings were reported by Sobh et al  and Vincenti et al  . In the study by Najarian et al  , they found that there was no difference in mean S Cr between LRD and their sibling controls.
The Cr Cl dropped significantly in all patients after nephrectomy compared to predonation total kidney function. Subsequently however, the study subjects had an increase in GFR that ranged from 5 to 64% (mean 34%) in the remaining kidney. Strandgaard et al  estimated the GFR of the remaining kidney over a period of two months after unilateral nephrectomy by measuring the clearance of 51Cr labeled ethylene diamine tetra-acetate (5ICrEDTA). They reported a 30% increase in GFR, which started on day five post nephrectomy and stabilized during the first year.
Mean renal volume of the remaining kidney increased by 15% compared to the preoperative values. This could be explained by cellular hypertrophy and hyperplasia mainly of the proximal convoluted tubules ,, . This concept is supported by the study using lithium clearance for the assessment of salt and water reabsorption by proximal tubules  . They concluded that the ability of the tubules to increase reabsorptive power represents compensatory hypertrophy of the nephrons  . Likewise, the secretory capacity of the proximal tubules had increased up to 75% of the preoperative levels six months after unilateral nephrectomy in human kidney donors  .
In conclusion, split renal function determination is desirable in LRD workup to help in selection of the kidney for donation. The kidney with better function should be left for the donor. Our study also shows that, compensatory changes occur in the volume and function of the remaining kidney and these changes occur early in the post donation period. Long-term follow-up studies are required to determine whether these functional and structural changes persist.
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Faissal A.M Shaheen
Consultant Nephrologist and Director, Jeddah Kidney Center, King Fahd Hospital, Jeddah
[Table 1], [Table 2], [Table 3]