Very low but stable glomerular filtration rate after living kidney donation: is the concept of "chronic kidney disease" applicable to kidney donors?

Renal prognosis and outcome of Japanese kidney donors, who have lower preoperative glomerular filtration rate (GFR) and are generally older than their counterparts abroad, have scarcely been investigated. Here, the longitudinal changes in renal function of Japanese kidney donors were studied to clarify the prevalence and consequences of low GFR. We reviewed charts of the living kidney donors and followed renal function by estimated GFR (eGFR, ml/min/1.73 m(2)) from the time of transplantation (n = 237), until 1 (n = 162) to 3 years after donation (n = 77). Median eGFR at the time of transplant was 78.7. GFR declined by approximately 40% at 1 year after donation, and as a result, most (85%) Japanese kidney donors developed chronic kidney disease (CKD) stage 3, with a median eGFR of only 48.0. The result, that the mean change in eGFR at 1-3 years after donation showed a steady increment of 0.97 ml/min/1.73 m(2) per year, was distinct from the generally accepted notion that GFR declines with age. This upward change was seen irrespective of the absolute values of eGFR at or 1 year after donation, even including a subgroup with the lowest postoperative eGFR of < 40. Most Japanese donors developed CKD stage 3 after donation but without subsequent progression, at least for several years. Although CKD is in general regarded to confer a significant risk for progressive kidney disease, this notion might not apply to living kidney donors with low GFR but without the risk factors for progression.