Relationship of FGF23 to indexed left ventricular mass in children with non-dialysis stages of chronic kidney disease

The aim of this study was to evaluate the association of serum intact fibroblast growth factor 23 (FGF23) concentrations with indexed left ventricular mass in children with non-dialysis stages 3-5 of chronic kidney disease (CKD). The study cohort comprised 83 children (51 boys; mean age 12.1 +/- 3.2 years) with a mean estimated glomerular filtration rate (eGFR) of 32.3 +/- 14.6 ml/min/1.73 m(2) who underwent clinic and ambulatory blood pressure measurement (ABPM), echocardiography and evaluation of biochemical markers of CKD-associated mineral bone disease. The mean left ventricular mass index (LVMI) was 35.9 +/- 8.5 g/m(2.7) (+/- standard deviation), with 30 (36.1 %) children showing left ventricular hypertrophy (LVH), all eccentric, as defined using age-specific criteria. For all subjects, the mean FGF23 concentration was 142.2 +/- 204.4 ng/l and the normalised distribution following log transformation was 1.94 +/- 0.39. There was significant univariate correlation of LVMI with GFR, body mass index (BMI) z-score and calcium intake, but not with 24-h systolic ABPM z-score, log intact parathyroid hormone or log FGF23. On multivariate analysis following adjustment for confounders, only elemental calcium content (g/kg/day) estimated from prescribed calcium-based phosphate binder dose (beta = 154.9, p < 0.001) and BMI z-score (beta = 2.397, p = 0.003) maintained a significant positive relationship with LVMI (model r (2) = 0.225). We observed no significant relationship of FGF23 with LVMI. Larger studies in children are needed to clarify the roles of calcium-containing phosphate binders and FGF23 with LV mass and their roles in the evolution of the development of adverse cardiovascular outcomes.