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Test ID FGF23 Fibroblast Growth Factor 23, Plasma

Useful For

Diagnosing and monitoring oncogenic osteomalacia


Possible localization of occult neoplasms causing oncogenic osteomalacia


Diagnosing X-linked hypophosphatemia or autosomal dominant hypophosphatemic rickets


Diagnosing familial tumoral calcinosis with hyperphosphatemia


Predicting treatment response to calcitriol or vitamin D analogs in patients with renal failure

Method Name

Immunometric Enzyme Assay

Reporting Name

Fibroblast Growth Factor 23, P

Specimen Type

Plasma EDTA

Specimen Required

Patient Preparation: Fasting preferred; nonfasting acceptable

Collection Container/Tube: Lavender top (EDTA)

Submission Container/Tube: Plastic vial

Specimen Volume: 1.5 mL

Specimen Minimum Volume

0.5 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Plasma EDTA Frozen (preferred) 90 days
  Refrigerated  14 days

Reference Values

Results may be significantly elevated (ie, >900 RU/mL) in normal infants <3 months of age.

3 months-17 years: ≤230 RU/mL

≥18 years: ≤180 RU/mL

Day(s) and Time(s) Performed


Performing Laboratory

Mayo Clinic Laboratories in Rochester

CPT Code Information


LOINC Code Information

Test ID Test Order Name Order LOINC Value
FGF23 Fibroblast Growth Factor 23, P 46699-5


Result ID Test Result Name Result LOINC Value
88662 Fibroblast Growth Factor 23, P 46699-5

Test Classification

This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the U.S. Food and Drug Administration.

NY State Approved