Background:

Rickets is characterized by an alteration in the normal mineralization of bone tissue and can be classified into acquired or hereditary forms. X-linked hypophosphatemic rickets (XLH) is the most common cause of hereditary forms. It is distinguished by an abnormal phosphorus metabolism attributed to a mutation in the PHEX gene (phosphate regulating endopeptidase analog, X-linked), located on the X chromosome. This abnormal gene affects the encoding of a metalloprotease responsible for decreasing serum levels of fibroblast growth factor - 23 (FGF-23), leading to an abnormal loss of phosphorus through urine. Patients present with bone deformities in the lower limbs, bone pain, short stature, and dental abnormalities. The diagnosis is made by the clinical presentation, associated with hypophosphatemia, phosphaturia and radiological findings suggestive of rickets and it is confirmed by molecular testing with the identification of the mutation in the PHEX gene.

Case presentation:

We describe the case of a 5-year-old patient diagnosed with XLH. Early diagnosis allowed to have an early treatment implementation, resulting in improved clinical outcomes.

Conclusion:

As a rare hereditary disease with onset in childhood and significant impact on longitudinal growth, bone health and potential impacts on the children quality of life, we aim to provide basic clinical tools for a comprehensive diagnostic approach of XLH.

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