Proteinuria and hyperphosphatemia are cardiovascular risk factors independent of GFR. We
hypothesized that proteinuria induces relative phosphate retention via increased proximal
tubule phosphate reabsorption. To test the clinical relevance of this hypothesis, we studied
phosphate handling in nephrotic children and patients with CKD. Plasma fibroblast growth
factor 23 (FGF-23) concentration, plasma phosphate concentration, and tubular reabsorption
of phosphate increased during the proteinuric phase compared with the remission phase in …