Reliability of plasma fibroblast growth factor 23 as risk biomarker in epidemiological studies measured over a four-month period.

BACKGROUND

Identified as a biomarker of altered calcium-phosphorus metabolism in chronic kidney disease, fibroblast growth factor 23 (FGF-23) can also be used as a biomarker of risk for cardiovascular disease in the general population. However, it is crucial to first evaluate the reproducibility (reliability) of plasma FGF-23 concentrations.

METHODS

We assessed the reliability of plasma FGF-23 concentrations using replicate blood samples taken four months apart of 207 participants from the European Prospective Investigation into Cancer and Nutrition-Potsdam Study.

RESULTS

Plasma FGF-23 concentrations at baseline (geometric mean: 24.7 RU/mL; 95% confidence interval [CI] in RU/mL: 21.8-27.9) were not significantly different from those measured four months later (geometric mean: 23.7 RU/mL; 95% CI in RU/mL: 20.6-27.1; P = 0.42). The intraclass correlation coefficients were 0.69 (95% CI: 0.62-0.76) for all; 0.64 (95% CI: 0.50-0.75) for men and 0.73 (95% CI: 0.64-0.81) for women.

CONCLUSIONS

Plasma FGF-23 concentrations showed good reliability over time. Our findings suggest that in epidemiological studies, a single plasma FGF-23 measurement may be sufficient to derive the relative risk in prospective cohort studies.