Test ID FL Fluoride, Plasma
Specimen Required
Supplies: Sarstedt Aliquot Tube, 5 mL (T914)
Collection Container/Tube: Green top (sodium heparin)
Submission Container/Tube: Plastic vial
Specimen Volume: 3 mL
Collection Instructions: Centrifuge and aliquot plasma into a plastic vial. Glass tubes are not acceptable.
Secondary ID
8641Useful For
Assessing accidental fluoride ingestion
Monitoring patients receiving sodium fluoride for bone disease or patients receiving voriconazole therapy
Method Name
Ion-Selective Electrode (ISE)
Reporting Name
Fluoride, PSpecimen Type
Plasma HeparinSpecimen Minimum Volume
1.2 mL
Specimen Stability Information
Specimen Type | Temperature | Time |
---|---|---|
Plasma Heparin | Refrigerated (preferred) | 14 days |
Ambient | 14 days | |
Frozen | 14 days |
Clinical Information
Fluoride induces bone formation by stimulating osteoblasts. Because fluorides increase bone density, they are used in dental preparations and as an antiosteoporotic agent. However, prolonged high exposure to fluoride produces changes in bone morphology consistent with osteomalacia, including prolonged mineralization lag time and increased osteoid thickness. The adverse skeletal effects of fluoride are associated with plasma fluoride greater than 4 mcmol/L. Chronic fluorosis may produce osteosclerosis, periostitis, calcification of ligaments and tendons, and crippling deformities.
Prolonged exposure to the fluoride-containing antifungal agent voriconazole can produce high plasma fluoride concentrations and bone changes (periostitis). Several other medicines also contain fluoride are used for treating skin diseases (eg, flucytosine, an antifungal) and some cancers (eg, fluorouracil, an antimetabolite).
Reference Values
<4.1 mcmol/L
Cautions
In solutions below pH 5, hydrogen ion (H[+]) complexes with the fluoride ion, thus reducing the free fluoride ion concentration and giving a falsely low reading.
At higher pH (>9), the hydroxyl ion (OH[-]) will interfere with electrodes, giving a falsely elevated reading.
Day(s) Performed
Tuesday
Report Available
2 to 8 daysPerforming Laboratory

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
82735