Thyroxine (T-4)
Label Mnemonic: | T4 |
Epic code: | LAB126 |
Order form: | Laboratory Requisition |
Supply order: | Supply Order Form |
Billing: | Billing Policies |
CPT code: | 84436 |
Specimen(s):
Plasma
Collection Medium:
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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:
AGE MALES/FEMALES 0 - 3 days 8.0-20.0 μg/dL 3 - 30 days 5.0-15.0 μg/dL 31 days - 1 years 6.0-14.0 μg/dL 1 - 5 years 4.5-11.0 μg/dL 6 - 18 years 4.5-10.0 μg/dL Normal adults 4.6 12.0 μg/dL
Comments:
Assay updated with increased tolerance to biotin on March 7,
2023.
Please print, complete and submit the Advance Beneficiary Notice (ABN) along with the Laboratory Requisition before shipping the specimen.
Please print, complete and submit the Advance Beneficiary Notice (ABN) along with the Laboratory Requisition before shipping the specimen.
Test Limitations:
The assay is unaffected by icterus (bilirubin is less than 37 mg/dL), hemolysis (Hb is less than 2300 mg/dL), lipemia (triglycerides is less than 2500 mg/dL) and biotin is less than 1200 ng/mL (criterion: recovery within plus or minus 10% of initial value). No interference was observed from rheumatoid factor (up to 2400 U/mL) and samples from dialysis patients. In vitro tests were performed on 15 commonly used pharmaceuticals. No interference with the assay was found. Autoantibodies to thyroid hormones can interfere with the assay. The risk of interference from potential immunological interactions between test components and rare plasma has been minimized by the inclusion of additives. In rare cases, interference due to extremely high titers of antibodies to ruthenium can occur. T4 reagent contains additives which minimize these effects. Extremely high titers of antibodies to streptavidin can occur in isolated cases and cause interference. For diagnostic purposes, the T4 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.
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.
See Additional Information:
Biotin Interference with Immunoassays
Biotin Interference with Immunoassays