Renal response to a protein meal in children with single kidneys.

The renal response of healthy adults to an oral protein load results in a significant increase of renal plasma flow (RPF) and glomerular filtration rate (GFR) 100 to 150 min after the meal. The renal response to protein loading of single kidney adults is unclear and it has not been evaluated yet in children. Therefore, we studied 8 children 10.2 +/- 1.1 years old, 6.7 +/- 1.41 years after nephrectomy (SK) and 4 healthy children (C). RPF was estimated by para-amino-hippurate clearance (Cpah) and GFR by inulin clearance (Cin) before and after an oral protein load of 1.5 g protein/kg body wt and expressed in ml/min/1.73 m2 BSA. Mean baseline Cin were similar in SK and in C (90 +/- 8 vs 103 +/- 12) while baseline Cpah was lower in SK (339 +/- 19 vs 481 +/- 36, p less than 0.005). After the meal GFR and RPF increased significantly in C (155 +/- 18 and 783 +/- 68, p less than 0.005 and p less than 0.05 vs baseline values, respectively) whereas no significant GFR and RPF changes were seen in SK (81 +/- 9 and 350 +/- 42, respectively). However, the 3 SK children with lower protein intake showed a mild vasodilating response. We conclude that in single kidney children hyperfiltration occurs at baseline conditions and the renal response to acute protein loading is partially or completely blunted, being modulated by protein intake.