Triiodothyronine - Free (T-3)
Label Mnemonic: | FT3 |
Epic code: | LAB137 |
Order form: | Laboratory Requisition |
Supply order: | Supply Order Form |
Billing: | Billing Policies |
CPT code: | 84481 |
Specimen(s):
Plasma
Collection Medium:
Plasma Separator Tube 4.5 mL |
Alternate
Collection Media:
Call laboratory for additional acceptable specimen collection containers.
Minimum:
3 mL whole blood in light green top or TWO
Microtainer® devices
Testing
Schedule:
24 hrs/day, 7 days a week, including holidays.
Turn Around
Time:
1 hour (upon receipt in laboratory)
Reference Range:
Less than 1 month: 1.4-5.5 pg/mL Less than 1 year: 2-6.9 pg/mL 1 - 5 years: 2.4-6.7 pg/mL 5 - 18 years: 2.3-5.5 pg/mL Adults: 2.57-4.43 pg/mL To convert results to ng/dL, multiply result x.1 To convert results to pmol/L, multiply result x 1.54
Comments:
Assay updated with increased tolerance to biotin on February 7, 2023.
Test
Limitations:
The assay is unaffected by icterus (bilirubin is less than 66 mg/dL), hemolysis (Hb is less than 1000 mg/dL), lipemia (Intralipid is less than 2000 mg/dL) and biotin is less than 1200 ng/mL (criterion: recovery within plus or minus 10% of initial value). 18 commonly used pharmaceuticals were tested in vitro. No interference with the assay was found. Therapeutic concentrations of acetylsalicylic acid and furosemide lead to elevated FT3 values. Autoantibodies to thyroid hormones can interfere with the assay. The risk of interference from potential immunological interactions between test components and rare sera has been minimized by the inclusion of suitable additives. In rare cases, interference due to extremely high titers of antibodies to streptavidin and ruthenium can occur. FT3 contains additives which minimize these effects. For diagnostic purposes, the FT3 findings should always be assessed in conjunction with the patient's medical history, clinical examination and other findings.
Methodology:
Electrochemiluminescence Immunoassay
Sample
Processing:
Centrifuge at a speed and time necessary to get barrier separation of plasma/serum and cells within 1 hour of collection. Send specimen in original tube. Do Not transfer to another tube.
Each sample must be labeled with at least TWO full patient identifiers (First/Last Name & DOB are sufficient for non-UIHC affiliated clients) to avoid sample rejection/delays.
Each sample must be labeled with at least TWO full patient identifiers (First/Last Name & DOB are sufficient for non-UIHC affiliated clients) to avoid sample rejection/delays.
Sample
Storage:
Refrigerate.
All sample storage requirements are intended for delivery to UIHC within 24 hours of collection for testing. If samples won't arrive in this time period, please call the UIHC Core Lab for alternative storage/shipping instructions (319-356-3527).
All sample storage requirements are intended for delivery to UIHC within 24 hours of collection for testing. If samples won't arrive in this time period, please call the UIHC Core Lab for alternative storage/shipping instructions (319-356-3527).
Transport
Instructions:
Place labeled specimen into zip-lock type biohazard bag; seal bag.
Place completed requisition into outside pocket of bag.
Transport in cooler with refrigerated coolant packs.
Place completed requisition into outside pocket of bag.
Transport in cooler with refrigerated coolant packs.
CPT Code:
84481
See Additional Information:
Biotin Interference with Immunoassays
Biotin Interference with Immunoassays