We have previously shown that the prevalence of albuminuria in donors is similar to age, gender and ethnicity matched NHANES controls. This cohort of 259 donors was asked to return for serial measurements of urinary albumin excretion.

After an overnight fast, donors underwent iohexol GFR measurement and also urine collection for either albumin to creatinine ratio (ACR) or protein urinalysis. Normoalbuminuria is defined as <30 mg/g Cr or <30 mg/dL; microalbuminuria 30-300 mg/g Cr or 30-100 mg/dL; macroalbuminuria ≥300 mg/g Cr or ≥100 mg/dL.

In total 210 donors completed serial urine protein measurements; mean age at the first evaluation was 52.9 ± 9.5 years, performed 12.0±8.9 years after donation; 79% were related to the recipient and 60% female. There was a marginally higher proportion of microalbuminuria at visit 1 (p=0.08) in those who did not complete the second visit (n=49) but the two groups were otherwise similar.

The second visit occurred 4.8±1.3 years after the first. 196 (93.3%) were normoalbuminuric at visit 1; 3 of which became microalbuminuric at visit 2. 14 donors had microalbuminuria at visit 1 and at visit 2, 11 were at normal levels; 2 remained microalbuminuric, and 1 became macroalbuminuic secondary to biopsy proven amyloidosis. Those who had microalbuminuria at visit 2 had a greater BMI and increased prevalance of diabetes and hypertension at the follow-up visit, p<0.05 for each (Table 1).

These data suggest that the majority of kidney donors remain normoalbuminuric even decades after donation and challenge the commonly held belief that donors have a higher risk of proteinuria than the general population.

Table 1. Comparison of normal vs. microalbuminuric donors at visit 2 (mean±SD or %)

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