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

Background: 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). Methods: 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 m² who underwent clinic and ambulatory blood pressure measurement (ABPM), echocardiography and evaluation of biochemical markers of CKD-associated mineral bone disease. Results: 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 (β = 154.9, p < 0.001) and BMI z-score (β = 2.397, p = 0.003) maintained a significant positive relationship with LVMI (model r² = 0.225). Conclusions: 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.