Lab marker · High

High FGF-23 (fibroblast growth factor 23): what it means

A FGF-23 (fibroblast growth factor 23) result above the normal range is considered high. Here is what a raised 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 result

What a high FGF-23 (fibroblast growth factor 23) can mean

  • Phosphate-wasting disorders — inherited hypophosphataemic rickets, or tumour-induced osteomalacia; cause low phosphate and soft bones.
  • Chronic kidney disease — rises early, before phosphate becomes abnormal; linked to worse outcomes.
  • High dietary or supplemental phosphate load.
  • Certain iron formulations — some intravenous irons can raise FGF-23.

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.

Keep reading

One value is a snapshot. Upload the full test to see every marker explained together.

Upload your test - free

Mediora.AI is informational - interpretation, not a diagnosis. A single out-of-range value is common and often benign; always discuss decisions with your doctor.