Early glomerular filtration rate changes in living kidney donors and recipients: an example of renal plasticity

Abstract

Background: In living kidney transplantation there are two different individuals, a healthy donor and a renal transplant recipient. This is an excellent human model to study factors that influence kidney function in the context of reduced renal mass and the adaptation of two comparable kidneys to different metabolic demands.

Methods: We analyzed the changes in measured glomerular filtration rate (GFR, iohexol) from pretransplantation to 12 months after transplantation in 30 donor-recipient pairs. Each donor was compared with his/her recipient. We defined a priori three different groups based on GFR differences at 12 months: donor > recipient (Group A; 78 ± 8 versus 57 ± 8 mL/min), donor < recipient (Group B; 65 ± 11 versus 79 ± 11 mL/min) and donor ≈ recipient (Group C; 66 ± 7 versus 67 ± 7 mL/min). Other factors like donor/recipient mismatches in body mass index (BMI), surface area and gender were evaluated.

Results: In Group A donors were mostly male and recipients were female (75% each). Donors had a higher baseline weight than their recipients. During follow-up, weight remained stable in donors but increased 7% in recipients. In Group B donors were mostly female (60%) and recipients male. At baseline, donors had a lower weight than recipients. At 12 months, weight was stable in donors but increased in recipients. In Group C donors were mostly (75%) female and recipients male. At baseline, donors had a higher BMI than their recipients. At 12 months, BMI was stable in donors but increased 14% in recipients. In multivariable analysis, higher GFR at 12 months was associated with higher baseline weight and GFR in donors and with male gender and higher baseline weight in recipients.

Conclusions: Kidneys from living donors are more 'plastic' than originally thought and respond to metabolic demands and weight changes of their new host. These changes should be taken into account when assessing GFR outcomes in this population.

Keywords: body mass index; gender; glomerular filtration rate; kidney transplantation; living donors.

FIGURE 1:

Measured GFR and weight changes in donor-recipient pairs grouped according to the difference in GFR at 12 months after transplantation. (Left panel) Group A: GFR higher in donors than recipients. (Middle panel) Group B: GFR lower in donors than recipients. (Right panel) Group C: mGFR comparable between donors and recipients. Donors: black circles; recipients: white circles.

FIGURE 2:

Measured GFR changes in donor-recipients pairs grouped by males who donated to females and females who donated to males. (Upper panels) Donors with greater BSA than their recipients. (Lower panels) Donors with lower BSA than their recipients. Donors: black circles; recipients: white circles.