Monitoring response to conventional treatment in children with XLH: value of ALP and Rickets Severity Score (RSS) in a real world setting

Research output: Contribution to journalArticlepeer-review

Authors

  • Suma Uday
  • Nicholas Shaw
  • M Z Mughal
  • T Randell
  • Wolfgang Högler
  • And 2 others
  • R Santos
  • Raja Padidela

Colleges, School and Institutes

Abstract

Introduction
X-linked hypophosphataemia (XLH) is conventionally managed with oral phosphate and active vitamin D analogues.

Objectives
To evaluate long term treatment response by assessing biochemical disease activity [serum alkaline phosphatase (ALP)], radiological rickets severity score (RSS), growth and morbidity in patients with XLH on conventional therapy and assess the correlation between serum ALP and RSS.

Methods
XLH patients from 3 UK tertiary centres with ≥3 radiographs one year apart were included. Data was collected retrospectively. The RSS was assessed from routine hand and knee radiographs and ALP z scores were calculated using age-specific reference data.

Results
Thirty-eight (male = 12) patients met the inclusion criteria. The mean ± SD knee, wrist and total RSS at baseline (median age 1.2 years) were 2.0 ± 1.2, 1.9 ± 1.2 and 3.6 ± 1.3 respectively; and at the most recent clinic visit (median age 9.0 years, range 3.3–18.9) were 1.6 ± 1.0, 1.0 ± 1.0 and 2.5 ± 1.5 respectively. The mean ± SD serum ALP z scores at baseline and the most recent visit were 4.2 ± 2.3 and 4.0 ± 3.3. Median height SDS at baseline and most recent visit were −1.2 and −2.1 (p = 0.05). Dental abscess, craniosynostosis, limb deformity requiring orthopaedic intervention and nephrocalcinosis were present in 31.5%, 7.9%, 31.6% and 42.1% of the cohort respectively. There was no statistically significant (p > 0.05) correlation between ALP z scores and knee (r = 0.07) or total (r = 0.12) RSS.

Conclusions
Conventional therapy was not effective in significantly improving biochemical and radiological features of disease. The lack of association between serum ALP and rickets severity on radiographs limits the value of ALP as the sole indicator of rickets activity in patients receiving conventional therapy.

Details

Original languageEnglish
Article number116025
JournalBone
Volume151
Early online date28 May 2021
Publication statusE-pub ahead of print - 28 May 2021