Fibroblast Growth Factor 23 is one of the endocrine hormones. These hormones are secreted directly into the bloodstream and target tissues located far from the glands that produce them. In addition to the pituitary, thyroid, adrenal, pancreas, and many other glands, bones also secrete endocrine hormones.
Fibroblast Growth Factor 23 (FGF23) is an endocrine hormone secreted by bones, and it mainly targets the kidneys and parathyroid glands.
What Is FGF23?
Fibroblast Growth Factor 23 (FGF23) is produced by osteocytes (mature bone cells embedded in mineralized bone) and osteoblasts (bone-forming cells) in bone tissue. Osteocytes are the primary producers, while osteoblasts make a small contribution.
FGF23 primarily targets the kidneys and parathyroid glands, where it helps regulate mineral balance. It reduces renal phosphate reabsorption, thereby promoting phosphate excretion. It also inhibits 1α-hydroxylase to suppress the activation of vitamin D.
It also modulates parathyroid hormone (PTH) secretion, creating a tightly regulated feedback loop among the bone, kidney, and parathyroid glands.
Why Measure FGF23?
Fibroblast Growth Factor 23 is an early biomarker of phosphate imbalance and declining kidney function. It is instrumental for evaluating models or samples related to chronic kidney disease, as FGF23 levels often rise before noticeable changes in serum phosphate or creatinine.
Measuring FGF23 also helps monitor:
- Genetic and metabolic bone disorders, such as hypophosphatemic rickets
- Disorders caused by abnormal phosphate handling
Researchers use the human FGF23 ELISA kit to measure Fibroblast Growth Factor 23 and assess how drugs influence phosphate regulation and vitamin D metabolism.
Methods to Measure FGF23 Concentrations
Serum vs. Plasma vs. Cell Culture Supernatants
Fibroblast Growth Factor 23 can be measured in serum, plasma, or cell culture supernatants.
Serum
Serum provides stable, consistent results.
Plasma
Depending on the anticoagulant used, plasma may minimize clotting-related interference.
Cell culture supernatants
These are used in experimental studies focused on FGF23 secretion from specific cell types.
Types of FGF23 Assays
Intact FGF23 assays
These assays are preferred in the evaluation of actual physiological activity, as they measure only the full-length, biologically active hormone.
C-terminal FGF23 assays
These assays help study disorders involving altered FGF23 secretion or degradation, as they detect both the intact hormone and its cleavage fragments.
Sandwich ELISA Technique
It is the most commonly used assay that uses a capture antibody and a detection antibody. The capture antibody binds to a site on the FGF23 molecule, immobilizing it. The detection antibody linked to an enzyme binds to a different site on the molecule.
Adding the TMB substrate causes the enzyme to generate a colorimetric change, which is then measured. A human FGF23 ELISA kit for sandwich ELISA offers excellent sensitivity, specificity, and reproducibility.
How to Interpret FGF23 Levels
What Elevated FGF23 Means
Elevated Fibroblast Growth Factor 23 levels indicate disrupted mineral metabolism or increased activation of phosphate-regulatory pathways. High concentrations are associated with chronic kidney disease, phosphate loading, iron deficiency, or inflammation. Elevated FGF23 also reflects overproduction by FGF23-secreting cells.
Researchers use higher concentrations to study early molecular changes that precede phosphate retention, vitamin D suppression, and alterations in PTH regulation.
What Low FGF23 Means
Low FGF23 concentrations in research indicate reduced transcriptional activity in osteocytes, impaired secretion, or altered protein processing. They are also associated with suppressed FGF23 signaling pathways.
Applications of FGF23 Measurement in Research
Conclusion
Fibroblast Growth Factor 23 measurement is a critical tool in both translational and basic research. It not only helps understand bone–kidney endocrine interactions but also supports the development of new biomarkers and targeted therapies for phosphate-related disorders.
This article was written for WHN by This article was written for WHN by Cynthia Lee is the President of AAA Biotech (AAA Bio / AAABio), a company specializing in highly validated and characterized monoclonal/polyclonal antibodies, recombinant proteins, and ELISA kits.
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