Central Body Fat Distribution Research and Kidney Function

In the April 2024 issue of the CJASN, Westenberg et al. published their research on Central Body Fat Distribution and Kidney Function after Living Kidney Donation.1 Because the association between central fat distribution and kidney function after living kidney donation remains unknown, the study set out to answer an important question on living kidney donor safety. Are body mass index (BMI) and central body fat distribution measures associated with kidney function after a donor nephrectomy in a group of normal-sized donors? I have a lot of interest in this research area because I received a living donor kidney transplant. The investigators attempted to answer this question by leveraging the data contained in the TransplantLines Biobank and an ongoing prospective study to assess short and long-term outcomes after solid organ transplantation and donation. Study measurements were performed at four different intervals with preselected measurements: As an element of the donor screening process before nephrectomy. After donor nephrectomy at 3 months, 5 years, and 10 years. Study measurements consisted of weight (BMI), waist circumference, waist-to-height ratio, and measured GFR. While the study results using unadjusted linear regression analysis for BMI did not show an association with postdonation measured GFR, adjusting for sex, age, and predonation GFR did demonstrate a negative relationship. The negative association with kidney function occurred for male donors at all three measurement points after donation. For women, it was limited to only 3 months and 5 years after donation. The results for waist circumference were similar to weight and kidney function. Linear regression analyses that were adjusted for sex, age, and predonation GFR demonstrated that higher waist circumference was significantly associated with lower measured GFR at the three intervals after donation for male donors. Like weight in female donors, the association was significant at only 3 months and 5 years. After adjusting for age, sex, and predonation GFR, a similar negative association was observed for waist-to-height ratio at the three measurement points for male donors. For female donors, the decline in kidney function was limited to 3 months after donation. The conclusion of the study showed that higher BMI, waist circumference, and waist-to-height ratio were significantly associated with lower GFR after living kidney donation. The subject of living donor safety is very personal and important to me. I saw first-hand the challenges faced by my living donor. Although my living donor's company would not provide paid medical leave, she remained undaunted in her desire to donate her kidney to me. Despite this financial obstacle, she never once hesitated in her act of mercy and compassion to restore my health. This example is why the National Kidney Foundation has championed the Living Donor Protection Act (H.R. 1240).2 This legislation would protect living donors and remove barriers to donation. The bill clarifies that living organ donors may use time granted through the Family and Medical Leave Act to recover from organ donation. This experience has shaped my belief that the kidney transplant community must always strive to improve support and care of living kidney donors throughout their postdonation journey. In many ways the living kidney donor is overlooked and not recognized adequately for their role in transforming the lives of kidney transplant recipients and their families. With this as background, therefore, this research resonated deeply with me and is aligned with my professional interests in advocating for the care of living kidney donors. Recommendations: Additional Research: One of the limitations of this study was that the study was conducted in normal-sized donors. The logical question that follows is what the GFR is in individuals who are slightly obese or obese. Will this result in a steeper decline in kidney function? In addition, I would like to see central body distribution research conducted in kidney transplant recipients. It is my hypothesis that the lack of rehabilitation after kidney transplantation has contributed to suboptimal long-term outcomes in the United States. Postdonation Care: As we have maintained our friendship with my donor, I have always asked her about her health and kidney function. I have always received the same response, "It is fine." Because her responses have lacked specific aspects of care, my perception has formed that she has not followed a care plan specific to having a nephrectomy. Research like central body fat distribution will have a limited effect if it is not put into clinical practice. Collaboration: The Scientific Registry of Transplant Recipients formed the Living Donor Collective3 in 2018 as a pilot project and has grown into an established registry to assess long-term outcomes of living donor candidates and donors. I would like to see the Living Donor Collective collaborate and leverage the registry experience of organizations such as TransplantLines.