# Office Blood Pressure and Obesity in Children with X-Linked Hypophosphatemia

## TL;DR

Children with X-linked hypophosphatemia have higher blood pressure and obesity rates compared to healthy children, with BMI being a key factor.

## Contribution

This study provides new evidence on elevated blood pressure and its association with obesity in pediatric XLH patients.

## Key findings

- Median systolic and diastolic blood pressure were significantly higher in XLH patients compared to healthy children.
- Obesity, hypertension, and high-normal blood pressure were more prevalent in the XLH cohort.
- BMI was significantly correlated with both systolic and diastolic blood pressure in XLH patients.

## Abstract

X-linked hypophosphatemia (XLH) is the most common inherited form of hypophosphatemic rickets. Children with XLH have an increased risk of obesity, which may promote high blood pressure, but data on blood pressure in XLH are inconclusive. We aimed to assess blood pressure and its determinants in pediatric XLH patients. We conduct a prospective, multicenter observational study of children with XLH in Germany and Switzerland. Office blood pressure and body mass index (BMI) were annually measured in 128 pediatric XLH patients with a median follow-up of 2 years (range 1–6). Potential predictors of blood pressure were investigated by Spearman correlation. Seventeen percent of patients were treated with phosphate supplements and active vitamin D for a median of 8 years, 83% of patients received burosumab for 2.3 years with 3.1 years of prior treatment with phosphate supplements and active vitamin D. Median systolic (0.75 z-score) and diastolic (0.32 z-score) blood pressure and BMI (0.72 z-score) were increased compared to healthy children (each p < 0.01). The prevalence of obesity (9.8% vs. 3%), arterial hypertension (26.2% vs. 5%), and high-normal blood pressure (22.9% vs. 5%) was higher in the XLH cohort compared to the general pediatric population (each p < 0.001). Spearman rank correlation analysis revealed significant associations between both systolic (r = 0.24; p < 0.01) and diastolic (r = 0.20; p < 0.05) blood pressure with BMI, while the mode of treatment, i.e. burosumab versus phosphate supplements and active vitamin D, was no significant correlate. Children with XLH present with elevated office blood pressure values, associated with elevated BMI.

The online version contains supplementary material available at 10.1007/s00223-025-01363-z.