Assessment of glomerular functions in renal donors before and after donation

Abstract

Growth of residual renal tissue in response to loss of other renal tissue is termed as compensatory hypertrophy. The functional adaptation is characterized by an increase in GFR which began 2 weeks after unilateral nephrectomy due to growth of the remaining kidney. Although increases in total renal weight have been reported in 24 hours, the total increase of about 50% in mass following unilateral nephrectomy is not achieved for 2 to 4 weeks. The degree of loss of renal mass is a key determinant of compensatory growth. Aim of this study is to observe the rate and extent of recovery in renal function in the post donation period after kidney donation. The objective is to follow the progressive changes in three parameters of renal function namely plasma creatinine level, plasma urea level and the creatinine clearance values in the preoperative and in different stages of postdonation period. 18 renal donors, 12 females and 6 males, who were closely related to recipients, were selected. This study was done in renal donors attending the nephrology department in Rajiv Gandhi Government General Hospital, Madras Medical College, Chennai 03. After obtaining written consent from donors the study was done after eliciting a proper history. There was significant difference in creatinine clearance values in different stages of post donation period as compared with the pre operative values and significant difference in creatinine clearance values in the pre operative and in different stages of post-donation period. Plasma Urea showed a rise of 3% in 2 week period post donation as compared to pre donation levels, but this fell by 2.5% resulting in only a 0.5% rise at the end of 6 week period post donation, with no further decrease during the study period. Statistical analysis by Anova showed no significant difference in plasma urea levels in the postdonation period as compared to pre donation levels. Plasma Creatinine showed a rise of 8% in 2 week period post donation as compared to pre donation levels, but this fell by 3% resulting only in 5% rise at the end of 6 week period post donation with no further decrease during the study period. Statistical analysis by Anova showed no significant difference in plasma creatinine levels in the post donation period as compared to pre donation levels. Creatinine Clearance of the study showed that there was significant difference in Creatinine Clearance of post donation period as compared to pre donation levels. The mean Creatinine Clearance value was approximately 58% of pre donation value at end of 12 weeks. Hence this study confirms that there is a mild improvement in the function of surviving kidney after renal donation as indicated on 8% rise in creatinine clearance by end of 12 weeks. There is a structural and functional adaptation during compensatory hypertrophy, which is a glomerular hyperplasia as well as hypertrophy and renal tubular cell hypertrophy. The results indicate that there is a very slight but significant increase in creatinine clearance. Other studies have indicated that there is a 10-15% increase in the SNGFR after nephrectomy or destruction of nephrons by disease.