Fibroblast Growth Factor 23 in COVID-19: an Observational Study.

Introduction: Fibroblast growth factor 23 (FGF23) belongs structurally to the endocrine FGF protein family, which also includes FGF19 and FGF21. In the past decade, FGF23 has emerged as a possible diagnostic, prognostic biomarker, and therapeutic target in several conditions. Data about COVID-19 and FGF23 is still limited, yet they suggest interesting interactions. Objective: In the present study, the levels of FGF23 were investigated in COVID-19 patients. These levels were also correlated with other inflammatory markers. Materials and methods: In our prospective observational study, blood samples were collected from 81 patients admitted with COVID-19 (31 males and 50 females). We analyzed the relation of serum FGF23 levels with biochemistry, total blood count, coagulation parameters, and demographic data. Results: The distribution of FGF23 serum levels according to sex and age (n(28-40)=8, n(41-60)=28, n(65-75)= 25, n(75+)=20) was similar. No significant correlation between FGF23 and any other biochemistry, total blood count, and coagulation parameter was revealed in the whole sample. Nevertheless, there was a variation in the results among different age groups. Conclusion: FGF23 levels seem to vary in symptomatic COVID-19 infection, but well-organized studies with larger numbers of patients in each group are needed to determine any reliable correlation between FGF23 and other laboratory parameters.