Identification of predictors of the decrease in kidney function after live kidney donation may help expand the living donor pool or identify donors for long-term medical follow up. In this study, we determined the association of demographic factors (donor age at transplantation, gender, body mass index), pre-donation kidney function (eGFR), and time zero kidney allograft biopsy findings (glomerular diameter and glomerular volume determined by the Weibel-Gomez method) with the percent decrease in pre-donation eGFR one year after live kidney donation among n=60 live kidney donors in our centre between 2000-9. The inclusion criteria required each patient to have an adequate time zero kidney biopsy as well as an eGFR recorded immediately before and one year post-kidney donation. The mean±std pre- and post-donation eGFR were 93±14 and 61±15 ml/min/1.73m2, respectively. The mean±std (median, Q25,Q75) percent change in eGFR after donation was 34±12, (37,31,41)%, and 91% had ≥30% decrement in eGFR. There was a mean±std of 11±5 glomeruli available for analysis in each time zero implant biopsy: the mean glomerular diameter was 163±17 ¯o;m, while the mean estimated glomerular volume was 2.81±0.98•10^6 ¯o;m3. No donors had glomerulomegaly (defined by volume ≥6.81•10^6 ¯o;m3).

In regression analyses, age at time of kidney donation was associated with the percent drop in kidney function after donation (3% greater decrement in pre-donation eGFR for each decade older, p=0.018), but there was no association with pre-donation eGFR, glomerular diameter, glomerular volume, donor BMI, race, or gender (data not shown).

We conclude that the percent decrement in eGFR post-kidney donation is variable, and associated with donor age at transplantation. The absence of an association between glomerular size and volume with the change in kidney function after donation in this study may be due to conservative donor selection, and these parameters may still prove useful in the selection of donors with more marginal levels of pre-donation kidney function.

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