True living donor kidney weight-to-recipient body weight ratio influences posttransplant 1-year renal allograft function

Body weight difference between donor and recipient is an important affector of early graft function after renal transplantation

BACKGROUND

Poor early graft function (EGF), a frequent complication of kidney transplantation, can be caused by many risk factors, including donor kidney and body weights.

METHODS

We studied the relationship to early graft function in a rat kidney transplantation model among 3 indices: ratio of graft to body weight; ratio of native kidney to body weight, and weight difference/body weight of the recipient. We categorized 2 groups based on contralateral nephrectomy at day 1 (G1) or day 3 (G2) after transplantation. EGF was evaluated by measuring serum creatinine levels at day 1 after bilateral nephrectomy.

RESULTS

The 3 indices, ie, weight difference/body weight of recipient (G1 and G2: P < .0001), ratio of native kidney to body weight (G1: P < .0001; G2: P = .0013), and ratio of graft to body weight (G1: P = .0064; G2: P = .014) strongly correlated with EGF regardless of the time of contralateral nephrectomy.

CONCLUSIONS

The index of weight difference/body weight of recipient sensitively and predominantly influenced EGF, which probably reflects the systemic metabolic profile.

Graft volume as the surrogate marker for nephron number affects the outcomes of living-donor kidney transplantation

Post-transplant outcome of kidney allografts depends on various factors, one of which may be the compatibility in volume between graft and recipient. However, previous studies adjusted the graft volume only for recipient's size. As the adjusted graft volume for donor's size would be substituted of nephron number more accurately, we adjusted the graft volume for both recipient's and donor's sizes. In 351 cases of living-donor kidney transplantation, we found that the adjusted graft volume for both recipient's and donor's body surface areas (BSAs) yielded larger area under the curves for the transplant outcomes than looking only at the adjusted volume for the recipient's BSA. The recipients were separated into two groups according to the low and high adjusted graft volumes. During the follow-up period (mean 55.6 months), the low-graft-volume group conferred greater risk of rejection, chronic change, glomerulonephritis, and graft loss than the high-graft-volume group (all p's < 0.05). However, the frequency of T-cell infiltration, as evaluated in protocol biopsy, was not different between the two adjusted graft volume groups. In conclusion, the graft volume as the surrogate marker for nephron number should be considered in kidney transplantation, especially in otherwise similar donor conditions.

The effect of donor/recipient body surface area ratio on outcomes in pediatric kidney transplantation

In pediatric kidney transplantation, the effect of inadequate nephron dosing on graft survival remains undetermined. The aim of this study was to assess the use of D/R BSA, as a reliable indicator of adequate nephron dosing, and eventually a tool to optimize pediatric graft allocation. Following Institutional Review Board approval, we reviewed deceased donor pediatric kidney transplantation (N = 156). We divided patients into three groups, based on D/R BSA: A < or =0.8; B 0.81-1.19; C > or =1.2. Five-yr graft survival rates in the groups were: A 82.0%; B 94.9%; C 97.1% (p = 0.01). Group C had the lowest rate of acute rejection, suggesting a protective effect of increased D/R BSA (group A = 35.7%, group B = 38.9%, group C = 18.8%; p = 0.029). The logistic regression analysis showed that decreased D/R BSA ratio is a risk factor for loss of graft function, at one and five yr [i.e., group A OR 6 (95% CI 1.14-39.30, p = 0.015) and OR 4.49 (95% CI 1.46-13.79, p = 0.009), respectively]. We conclude that for pediatric recipients, D/R BSA is a valuable adjunct when determining long-term graft survival. Its utility may avoid an alloimmune-independent risk factor, increasing the long-term protective value of a good matching policy.

Kidney weight and volume among living donors in Brazil

CONTEXT AND OBJECTIVE

The present study was performed to measure kidney weight and volume among living donors of both sexes in Brazil.

DESIGN AND SETTING

This was a cross-sectional survey carried out between December 2001 and August 2004.

METHODS

Kidney transplantations from 219 living donors were analyzed for this study. The kidneys were weighed in grams on a single-pan digital balance just after drainage of the perfusion fluid and removal of the perirenal fat. The kidney volume was determined in milliliters by water displacement.

RESULTS

The mean age at nephroureterectomy was 44 +/- 9.5. The donor organs came from the left side in 172 cases and from the right side in 47 cases. The weights and volumes of the right and left kidneys were, respectively, 169.83 +/- 29.91 g and 157.38 +/- 31.84 ml; and 173.00 +/- 33.52 g and 160.34 +/- 34.40 ml. The differences between the sides were not significant.

CONCLUSIONS

According to the present study, kidney weight cannot be the only factor determining the side on which nephroureterectomy is performed, because of the lack of statistical significance between the two sides. On average, females donate lower nephron doses than males do, which could in some transplants result in allograft damage.

Gender-related differences of renal mass supply and metabolic demand after living donor kidney transplantation

Kidney donation from female donors to male recipients has been reported to be associated with decreased allograft survival. Whether there was a gender-related inadequacy between donor nephron supply and recipient functional demand was investigated in this study. One hundred ninety-five living donor kidney transplant recipients that had neither ischemic injury, episode of rejection, nor any complication were included. Weights and heights of both donors and recipients were recorded to calculate body surface area, lean body weight, and body mass index. The donated kidney was weighed just after cold flush, and the recipient's serum creatinine (Scr) was measured on a daily basis post-operatively. When the recipient's Scr reached the baseline, a 24-h urine was collected for the amount of proteinuria (Upr), creatinine excretion (Ucr) and creatinine clearance (Ccr) calculation. The effect of donor and recipient gender was analysed by independent sample t-test. On average, male donors and recipients were heavier and taller than females. However, the mass of kidneys donated from men and women were not statistically different. The gender-related differences in post-transplant Scr and Ucr of recipients were associated with the differences in the parameters of metabolic demands of recipients rather than with the weight of implanted kidney (renal mass supply) or with pre-operative renal functions of donors (functional supply). The early graft function is not determined by donor gender. The effect of recipient gender on the graft function depends on the metabolic demands, which are higher in male recipients.

Metabolic demand and renal mass supply affecting the early graft function after living donor kidney transplantation

BACKGROUND

Graft mass has been demonstrated to be a determinant of outcome after kidney transplantation. An insufficient nephron might fail to meet the metabolic demands of the recipient and lead to hyperfiltration.

METHODS

The study population was restricted to live donor transplants demonstrating immediate function that had neither ischemic injury, episodes of rejection, nor any complications that resulted in a functional decrease of the graft. The donated kidney was weighed just after cold flush, and the recipient's serum creatinine (Scr) was measured on a daily basis postoperatively. When the recipient's Scr reached the baseline, the recipient's 24-hour urine was collected for the amount of proteinuria (Upr), creatinine excretion (Ucr), and creatinine clearance (Ccr) calculation. As the parameters of the metabolic demands of donor and recipient, body weight, height, body surface area, lean body weight, and body mass index were noted. Pearson correlation and linear regression were carried out.

RESULTS

The graft function, as measured by Scr, Ucr, and Upr, was not directly correlated with the graft weight but rather correlated with the ratios of graft weight to the parameters of recipient's metabolic demands. As recipient size increased, the metabolic demand has increased. The parameters of recipient's metabolic demands were directly correlated with Scr and Ucr, rather than with Upr.

CONCLUSION

During living donor and recipient matching, both the potential sizes of the donated kidney and the recipient should be considered in terms of the early graft function after transplantation.

Effect of donor/recipient body weight mismatch on patient and graft outcome in living-donor kidney transplantation

BACKGROUND/AIMS

There have been conflicting reports showing that kidneys from small donors may be at risk for graft loss if they are transplanted into large recipients. The aim of this work was to examine the donor/recipient body weight ratio (D/RBWR) on patient and graft outcome.

METHODS

During the period from January 1990 to January 2002, 856 kidney transplants were performed. Of these, 776 kidney transplant recipients were selected after exclusion of pediatric, second transplant patients and those with a body mass index of 35. All patients achieved a minimum follow-up of 1-year. According to D/RBWR, patients were divided into 3 groups: low (0.9), medium (0.91-1.2) and high (1.2). Data were collected on graft function, acute and chronic rejection, post-transplant complications, and 1- and 5-year graft and patient survival.

RESULTS

There was a statistically significant increase in the incidence of chronic rejection, post-transplant hypertension and diabetes mellitus in the low group. The incidence and frequency of acute rejection episodes were nearly the same in the 3 groups. Graft function, estimated by serum creatinine at 1 year, was significantly lower in the low group. The 5-year graft and patient survival was 71, 80, 88 and 81, 85 and 92%, in the low, medium and high groups, respectively.

CONCLUSIONS

We conclude that a low D/RBWR may contribute to inferior long-term renal allograft survival. The hyperfiltration hypothesis due to low nephron mass in the low D/RBWR group may explain these findings.

Influence of allograft size to recipient body-weight ratio on the long-term outcome of renal transplantation

BACKGROUND

The critical nephron mass needed to meet the metabolic demands of an individual depends on the body-weight. This study evaluated the effect of the kidney transplant ultrasonographic size to recipient body-weight ratio (Tx/W) on the outcome of kidney transplantation.

METHODS

A consecutive series of 104 cadaveric renal transplants was studied. Transplant cross-sectional area (TXSA) was measured ultrasonographically in the first week after transplantation as an index of renal size. A 'nephron dose' index (Tx/W) was calculated by dividing TXSA by recipient weight and was used to define three groups of patients, with high (more than 0.45), medium (0.3-0.45) or low (less than 0.3) Tx/W ratios. Isotope glomerular filtration rate (GFR) measurements were made at 1, 6 and 12 months after transplantation.

RESULTS

The serum creatinine level was significantly lower in the first 5 years after transplantation in patients with a high Tx/W ratio than in those with a medium or low ratio. GFR measurements were marginally higher in the groups with a high and medium Tx/W ratio compared with the low Tx/W group. A statistically significant association between Tx/W ratio and graft survival was not found.

CONCLUSION

The renal transplant size to recipient weight ratio was an important determinant of long-term renal allograft function in this study. Extreme mismatching between allograft and recipient size should be avoided where possible, but the findings presented require confirmation in larger studies before clear recommendations can be made about size matching and kidney allocation.