Low FGF-23 (fibroblast growth factor 23): what it means
A FGF-23 (fibroblast growth factor 23) result below the normal range is considered low. Here is what a reduced FGF-23 (fibroblast growth factor 23) can point to, and when it is worth discussing with a doctor.
Reference range: assay-dependent (e.g. intact FGF-23 up to ~60 pg/mL); a hormone from bone that lowers phosphate — high levels cause phosphate wasting, and it rises early in kidney disease
Understand your full resultWhat a low FGF-23 (fibroblast growth factor 23) can mean
- Normal or low — the expected result outside these specific disorders.
- Rare disorders of too little FGF-23 activity — cause the opposite, high phosphate with calcification (tumoral calcinosis).
When to discuss with a doctor
FGF-23 is a specialist test rather than a routine one. It is most useful when a low blood phosphate with soft, aching bones suggests a phosphate-wasting disorder: a high FGF-23 points to an FGF-23-driven cause (inherited or, importantly, a phosphate-wasting tumour), which changes treatment. In chronic kidney disease it is used mainly in research and specialist assessment as an early marker of disturbed mineral metabolism. It is always interpreted alongside phosphate, calcium, PTH, vitamin D and kidney function, since these hormones work as a system. Mediora.AI shows FGF-23 in the context of phosphate and the other mineral markers so the pattern is visible; the interpretation belongs with your specialist team.
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One value is a snapshot. Upload the full test to see every marker explained together.
Upload your test - freeMediora.AI is informational - interpretation, not a diagnosis. A single out-of-range value is common and often benign; always discuss decisions with your doctor.