Longitudinal study of living kidney donor glomerular dynamics after nephrectomy

Abstract

ResultsResponse to donor nephrectomy in healthy humans. Twenty-one subjects underwent clinical, physiological, and radiological assessments immediately before, early after (median, 0.8 years), and late after (median, 6.1 years) (hereafter, pre-donation, early post-donation, and late post-donation) living kidney donation. A morphometric evaluation of glomeruli was performed on renocortical tissue that was obtained by wedge biopsy at the time of donor nephrectomy in 19 subjects. Baseline demographic, physio-BACKGROUND. Over 5,000 living kidney donor nephrectomies are performed annually in the US. While the physiological changes that occur early after nephrectomy are well documented, less is known about the long-term glomerular dynamics in living donors. METHODS.We enrolled 21 adult living kidney donors to undergo detailed long-term clinical, physiological, and radiological evaluation pre-, early post-(median, 0.8 years), and late post-(median, 6.3 years) donation. A morphometric analysis of glomeruli obtained during nephrectomy was performed in 19 subjects.RESULTS. Donors showed parallel increases in single-kidney renal plasma flow (RPF), renocortical volume, and glomerular filtration rate (GFR) early after the procedure, and these changes were sustained through to the late post-donation period. We used mathematical modeling to estimate the glomerular ultrafiltration coefficient (K f ), which also increased early and then remained constant through the late post-donation study. Assuming that the filtration surface area (and hence, K f ) increased in proportion to renocortical volume after donation, we calculated that the 40% elevation in the single-kidney GFR observed after donation could be attributed exclusively to an increase in the K f . The prevalence of hypertension in donors increased from 14% in the early post-donation period to 57% in the late post-donation period. No subjects exhibited elevated levels of albuminuria. CONCLUSIONS.Adaptive hyperfiltration after donor nephrectomy is attributable to hyperperfusion and hypertrophy of the remaining glomeruli. Our findings point away from the development of glomerular hypertension following kidney donation.

Renal Consequences of Diabetes After Kidney Donation

“…It is possible that since hyperfiltration is nearly complete in the first few years after donation, no additive hyperfiltration is taking place by the time diabetes develops. Moreover, hyperfiltration in kidney donors is mostly due to an increase in the glomerular surface area rather than augmentation in the intraglomerular pressure such as that seen with diabetes (28). …”

Hypertensive Kidney Injury and the Progression of Chronic Kidney Disease

“…We have further suggested hyperfiltration in normotensive models of reduced renal mass is accomplished without significant P GC increases through coordinated increases in glomerular filtration surface area (hypertrophy) and increases in single nephron plasma flow through proportionate afferent and efferent vasodilation 9,38 similar to that seen after uninephrectomy in kidney donors or during pregnancy. 39,40 In a sense, it is like growing new glomerular capillaries in situ . If there are increases in P GC , they are small and not likely to be pathogenic.…”

Neutrophil Gelatinase-Associated Lipocalin, Fibroblast Growth Factor 23, and Soluble Klotho in Long-Term Kidney Donors

“…This is associated with glomerular hypertrophy and an increase in renocortical volume. Adaptive hyperfiltration by the remaining kidney is maintained at a constant level for at least 6-8 years after donation [33]. Renal hyperfiltration is associated with an increased risk of developing hypertension and CVD, and there is an association between renal hyperfiltration and decline in eGFR [34].…”