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HelpTest Code 23FBG Fibroblast Growth Factor-23 (FGF23), In Situ Hybridization
Additional Testing Requirements
If additional interpretation or analysis is needed, request PATHC / Pathology Consultation along with this test.
Shipping Instructions
Attach the green "Attention Pathology" address label (T498) to the outside of the transport container before putting into the courier mailer.
Necessary Information
A pathology/diagnostic report and a brief history are required.
Specimen Required
Specimen Type: Tissue
Supplies: Pathology Packaging Kit (T554)
Submit:
Formalin-fixed, paraffin-embedded tissue block
OR
5 Unstained, positively charged glass slides; sections 4-microns thick
Useful For
Assessing fibroblast growth factor-23 (FGF23) expression
Method Name
In Situ Hybridization (ISH)
Reporting Name
Fibroblast Growth Factor-23, ISHSpecimen Type
SpecialSpecimen Stability Information
| Specimen Type | Temperature | Time |
|---|---|---|
| Special | Ambient (preferred) | |
| Refrigerated | ||
Reject Due To
| Wet/frozen tissue | Reject |
| Cytology smears | Reject |
| Nonformalin fixed tissue | Reject |
| Nonparaffin embedded tissue | Reject |
| Noncharged slides | Reject |
| ProbeOn slides | Reject |
| Snowcoat slides | Reject |
Clinical Information
Fibroblast growth factor-23 (FGF23) is a phosphaturic hormone that acts on the proximal renal tubules to block phosphate reuptake. Production of FGF23 by a particular mesenchymal tumor, phosphaturic mesenchymal tumor, is responsible for the great majority of cases of tumor-induced osteomalacia.
Interpretation
This test, when not accompanied by a pathology consultation request, will be reported as either positive or negative. If additional interpretation or analysis is needed, request PATHC / Pathology Consultation along with this test.
Cautions
Age of a cut paraffin section can affect immunoreactivity. Stability thresholds vary widely among published literature and are antigen dependent. Best practice is for paraffin sections to be cut within 6 weeks.
The charge of glass slides can be affected by environmental factors and subsequently may alter slide staining. Sending unsuitable glass slides can result in inconsistent staining due to poor slide surface chemistry.
Best practices for storage of positively charged slides:
-Minimize time slides are stored after being unpackaged
-Limit exposure to high humidity and heat
Method Description
In situ hybridization on sections of paraffin-embedded tissue.(Unpublished Mayo method)
Day(s) Performed
Monday through Friday
Report Available
5 to 8 daysSpecimen Retention Time
Until staining is completePerforming Laboratory
Mayo Clinic Laboratories in Rochester
Test Classification
This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.CPT Code Information
88365-Primary
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| 23FBG | Fibroblast Growth Factor-23, ISH | 104259-7 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| 620250 | Interpretation | 50595-8 |
| 620251 | Participated in the Interpretation | No LOINC Needed |
| 620252 | Report electronically signed by | 19139-5 |
| 620253 | Material Received | 81178-6 |
| 620254 | Disclaimer | 62364-5 |
| 620255 | Case Number | 80398-1 |
Forms
If not ordering electronically, complete, print, and send a Immunohistochemical (IHC)/In Situ Hybridization (ISH) Stains Request (T763) with the specimen.