Test name: Free Triiodothyronine
Order Code: FT3
Preferred Specimen: 2mL serum in a Serum Separator Tube (SST or Tiger-top)
CPT Code: 84481
Collection: Allow SST to clot in an upright position for 30 min, then centrifuge sample within 2 hours of collection. Refrigerate.
Special Instructions and Considerations: Samples should not be taken from patients receiving therapy with high biotin doses (i.e. > 5 mg/day) until at least 8 hours following the last biotin administration. Any influence that might affect the binding behavior of the binding proteins can alter the result of the free T3 tests (e.g. drugs, NTIs (Non-Thyroid-Illness) or patients suffering from FDH (Familial Dysalbuminemic Hyperthyroxinemia)). In in vitro studies the drugs Furosemide and Levothyroxine caused elevated free T3 findings at the daily therapeutic dosage level.
Transport Temperature: Refrigerated
Specimen Stability: 7 days refrigerated