Clinical significance of increased serum levels of FGF-23 in fibrous dysplasia. / Significado clínico del aumento de los valores séricos de FGF-23 en la displasia fibrosa.

ABSTRACT

INTRODUCTION AND OBJECTIVE: Fibrous dysplasia (FD) can be associated with the development of hypophosphatemic osteomalacia, caused by the production of FGF-23 by dysplastic bone tissue. This study analysed FGF-23 levels in patients with FD, and their association with disease activity and serum phosphate values. PATIENTS AND METHODS: Twelve adult patients with FD were included in the study. Clinical history, disease extension and activity and treatments received were reviewed, and the relationship of those values with FGF-23 and serum P levels was analysed. RESULTS: FGF-23 was elevated in 6/12 patients (50%). Patients with high FGF-23 levels had similar age and disease activity and extension than those who did not. No differences were observed in serum phosphate values between both groups (increased FGF-23 3.9±0.9 mg/dl vs. decreased FGF-23 3.5±0.6 mg/dl). In fact, none of the patients with increased FGF-23 had low serum phosphate values. CONCLUSION: Adult FD patients frequently present elevated FGF-23 values with no serum phosphate level repercussion, suggesting an alteration in the processing of this protein in the dysplastic bone tissue for this pathology.