Fibroblast Growth Factor 23 (FGF23), Serum/Plasma — Concentration
Measures FGF23, a hormone that helps regulate blood phosphate and active vitamin D. It may help evaluate bone and mineral disorders.
["FGF23 is most useful when interpreted with blood phosphate, calcium, vitamin D, kidney function, and other clinical findings."]
Key facts at a glance
- LOINC
- 53429-7
- Short code
- FGF-23 sp4 p chal Plas IA-aCnc
- Synonyms
- FGF-23 sp4 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 test measures fibroblast growth factor 23 (FGF23), a hormone made by bone and other tissues. FGF23 helps the kidneys control phosphate levels and the production of active vitamin D.
Why might I need this test?
A clinician may order it to investigate unexplained low blood phosphate, rickets, osteomalacia, or other bone and mineral metabolism disorders. It may also be used when calcium, phosphate, vitamin D, or kidney test results are unusual.
How is the test performed?
A blood sample is collected and separated into serum or plasma for laboratory measurement. The laboratory method may vary, so the test is generally reported as a concentration in the blood.
How do I prepare for the test?
Fasting is often not required, but the ordering clinician or laboratory should provide specific instructions. Continue prescribed medicines unless a clinician tells you to change them, because vitamin D, phosphate, calcium, and certain other medicines can affect the result.
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.
Elevated FGF23 may cause or contribute to low blood phosphate and low active vitamin D, potentially producing weakness, bone pain, or impaired bone mineralization. Increased FGF23 can occur with inherited phosphate-handling disorders, chronic kidney disease, and, less commonly, certain tumors that secrete FGF23.
Short name
FGF23 blood test
Frequently asked questions
Does a high FGF23 result mean I have cancer?
Why is FGF23 interpreted with other blood tests?
Can I use an FGF23 result to choose a vitamin D supplement?
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.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy