Dhayat NA, et al. - Researchers intended to define the phenotype of kidney stone formers (SF) with renal phosphate leak. They also studied the association of renal phosphate leak with stone history, stone composition and bone mineral density (BMD) in this cross-sectional analysis of a cohort of 555 idiopathic calcareous SF. They assessed renal phosphate transport by using the ratio of tubular maximum reabsorption of phosphate to glomerular filtration rate (TmP/GFR). SF showed a strong heritable component with regards to renal phosphate handling, which demonstrated correlation with parathyroid hormone (PTH), 25-hydroxy vitamin D (25(OH)D) and 1,25-dihydroxy vitamin D (1,25(OH)₂D), but not with fibroblast growth factor 23 (FGF23) levels. Furthermore, higher urinary calcium excretion and an increased prevalence of brushite stones related to a low TmP/GFR (ie, a renal phosphate leak).