Triiodothyronine (T-3)
Label Mnemonic: | TT3 |
Epic code: | LAB136 |
Order form: | Laboratory Requisition |
Supply order: | Supply Order Form |
Billing: | Billing Policies |
CPT code: | 84480 |
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 0.6-3.0 ng/mL 4 days - 1 year 0.9-2.6 ng/mL 1 year - 6 years 0.9-2.4 ng/mL 7 - 11 years 0.9-2.3 ng/mL 12 - 18 years 1.0-2.1 ng/mL Adults 0.8-2.0 ng/mL
Comments:
Assay updated with increased tolerance to biotin on March 7,
2023.
Test Limitations:
The assay is unaffected by icterus (bilirubin less than 35 mg/dL), hemolysis (Hb less than 2000 mg/dL), lipemia (triglycerides less than 1800 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 1500 U/mL) and samples from dialysis patients. Twenty-six commonly used pharmaceuticals were tested in vitro. No interference with the assay was found. Therapy with amiodarone can lead to abnormal thyroid hormone tests. Phenytoin, phenylbutazone and salicylates cause release of T3 from the binding proteins, thus leading to a reduction in the total T3 hormone level at normal fT3 levels. Auto-antibodies to thyroid hormones can interfere with the test. Pathological concentrations of binding proteins (TBG, albumin) can lead to total T3 values outside the normal range being found despite a euthyroid metabolic state (e.g. in NTI-patients, pregnancy, use of oral contraceptives). In such cases, determination of free T4 and/or free T3 may be indicated. The risk of interference from potential immunological interactions between test components and rare sera has been minimized by the inclusion of additives. For diagnostic purposes, the T3 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.
See Additional Information:
Biotin Interference with Immunoassays
Biotin Interference with Immunoassays