Hypertension and nephrology

[Novelties in the diagnosis and treatment of X-linked hypophosphatemia]

RUESZ György Sándor1, MIKES Bálint1, CSIZEK Zsófia1, HORVÁTH Orsolya1

APRIL 22, 2022

Hypertension and nephrology - 2022;26(02)

DOI: https://doi.org/10.33668/hn.26.009

[X-linked hypophosphataemia (XLH) is the most common inherited cause of phosphate wasting. Its pathogenesis is complex, determined by the dysregulation of phosphate homeostasis and bone metabolism. We review herein the pathophysiology of XLH leading to multiple manifestations, stages of diagnosis and the treatment strategies. XLH is now in the scientific interest of pediatric nephrology, because a new treatment modality, burosumab became available in Hungary. Burosumab is a monoclonal antibody against fibroblast growth factor 23 (FGF-23). XLH is caused by the loss of function mutations in ”phosphate regulating endopeptidase homolog, X-linked” (PHEX) gene, which results enhanced secretion of the phosphaturic hormone FGF-23. The diagnosis of XLH is based on signs of rickets and/or osteomalacia and decreased growth velocity in association with hypophosphataemia and renal phosphate wasting in the absence of vitamin D or calcium deficiency. Conventional treatment with oral phosphate supplementation together with active vitamin D (calcitriol or alfadiol) can improve bone metabolism, but only partial results can be achieved, and can promote side effects (nephrocalcinosis). The better understanding of the role of PHEX gene and FGF-23 levels in the pathomechanism helped to identify therapeutic options more properly. With monoclonal antibody therapy against FGF-23 the disease process can be interrupted, and complications can be prevented if the therapy is initiated in time. However, deformities already leading to disability cannot regress completely during burosumab therapy, highlighting the need of early diagnosis and the start of the biological treatment before complications.]

AFFILIATIONS

  1. Semmelweis Egyetem, I. Sz. Gyermekgyógyászati Klinika

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