# Specific associations of serum FGF23 and soluble Klotho with different types of left ventricular hypertrophy in hypertensive peritoneal dialysis patients: a cross-sectional study

## TL;DR

This study finds that high FGF23 and low soluble Klotho levels are linked to heart issues in hypertensive dialysis patients, with FGF23 showing a non-linear effect.

## Contribution

The study identifies FGF23 and soluble α-Klotho as potential biomarkers for left ventricular hypertrophy in peritoneal dialysis patients.

## Key findings

- Soluble α-Klotho is an independent protective factor against left ventricular hypertrophy (LVH).
- FGF23 is an independent risk factor for LVH with a non-linear relationship to LVMI.
- The FGF23-LVMI relationship is stronger in older patients and males.

## Abstract

This study aimed to investigate the association between serum fibroblast growth factor 23 (FGF23) and soluble α-Klotho levels with left ventricular hypertrophy (LVH) in hypertensive patients undergoing peritoneal dialysis (PD). We also sought to evaluate their potential as biomarkers of left ventricular remodelling and to analyze potential non-linear relationships with the left ventricular mass index (LVMI), including subgroup differences.

In this cross-sectional study, 124 hypertensive PD patients were enrolled. Serum concentrations of FGF23 and soluble α-Klotho were measured via enzyme-linked immunosorbent assay (ELISA). Echocardiography was used to assess left ventricular structure and define LVH. Multivariate logistic regression analysis was performed to evaluate the independent associations of these biomarkers with LVH. A restricted cubic spline (RCS) model was employed to explore non-linear relationships with LVMI.

The prevalence of LVH was 62.9%. After adjusting for gender, systolic blood pressure C–reactive, protein, haemoglobin, serum calcium, ejection fraction, serum phosphorus, and parathyroid hormone, multivariate analysis identified soluble α-Klotho as an independent protective factor against LVH (OR = 0.415, 95% CI: 0.247–0.643, P < 0.001), whereas FGF23 was an independent risk factor (OR = 1.260, 95% CI: 1.079–1.501, P = 0.005). RCS analysis revealed a significant non-linear relationship between FGF23 and LVMI (P < 0.001), with an inflection point at approximately 39.8 pg/mL. This association was more pronounced in patients aged >61 years and in males. The overall association between soluble α-Klotho and LVMI was not statistically significant.

Among hypertensive PD patients, serum soluble α-Klotho is an independent protective biomarker for LVH, while elevated FGF23 levels are associated with an increased risk of LVH, suggesting an interaction between the two. FGF23 demonstrates a non-linear association with LVMI, which is modified by age and gender. Concurrent measurement of FGF23 and soluble α-Klotho may help identify patients at high risk for cardiovascular remodelling, thereby informing risk stratification and personalized management strategies.