Fibroblast Growth Factor 23 (FGF23), Serum/Plasma — Immunoassay, Arbitrary Concentration
Measures FGF23, a hormone that helps the kidneys regulate phosphate and vitamin D. It may be used to evaluate disorders of mineral and bone metabolism.
["An FGF23 blood test helps evaluate how the body is regulating phosphate, calcium, and vitamin D."]
Key facts at a glance
- LOINC
- 53427-1
- Short code
- FGF-23 sp2 p chal Plas IA-aCnc
- Synonyms
- FGF-23 sp2 p chal Plas IA-aCnc
- Category
- liver
- Sample
- plasma
- Container
- Lavender-top (EDTA) or Green-top (Heparin)
- Units
- N/A
- Ref low
- 44
- Ref high
- 147
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- ia
- CPT
- 84075
- SNOMED
- 27550007
- Specimen volume
- 5 mL
- Stability
- Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 4–24 hours
- Order
- routine
What is this test?
This blood test measures fibroblast growth factor 23, or FGF23. FGF23 is made mainly by bone and helps control phosphate levels, calcium balance, and vitamin D activation.
Why might I need this test?
A clinician may order this test when there is unusual phosphate loss, suspected disordered bone mineralization, vitamin D regulation problems, or symptoms suggesting a phosphate-wasting disorder. Results are usually interpreted with calcium, phosphate, parathyroid hormone, vitamin D, and kidney function tests.
How is the test performed?
Blood is collected into a serum or plasma tube and analyzed using an immunoassay. The laboratory reports the FGF23 concentration in the units established for that assay.
How do I prepare for the test?
No special preparation is usually required unless your clinician gives specific instructions. Tell the care team about phosphate supplements, vitamin D products, and other medicines or supplements you take, because they may affect mineral metabolism.
Reference range
Adult: 44-147 U/LN/A
No special preparation required. Avoid fatty meals before the test if possible.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
An elevated FGF23 result may occur with conditions that cause the body to lose phosphate through the kidneys, including some bone disorders, vitamin D regulation abnormalities, and chronic kidney disease. In certain cases, it can be associated with a rare FGF23-producing tumor. A low result may be seen with some disturbances of calcium or phosphate regulation, so the result should be interpreted together with the other parts of the metabolic panel rather than by itself.
Short name
FGF23 Blood Test
Frequently asked questions
What does FGF23 measure?
Why is FGF23 tested with other blood tests?
Does an abnormal FGF23 result diagnose a specific condition?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
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Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy