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HelpTest Code T3C T3-Triiodothyronine, Total, Serum
Specimen Type
Blood
Container/Tube
Red Top
Offsite Collection Instructions
- Within 2 hours of collection the sample must be spun,
aliquoted
and transported refrigerated (2 –
8˚C). - Minimum volume of 250µl of serum
Turnaround Time
4 hours
Preferred Volume
4 mL
UCMC Collection Instructions
- Unspun whole blood samples need to be received in the
Laboratory Service Center within 2 hours of collection at room
temperature (15 – 25˚C).
STAT Turnaround Time
N/A
Test Usage
The determination of T3 may be utilized in the
diagnosis of T3-hyperthyroidism, the detection of early stages
of
hyperthyroidism and for indicating a diagnosis of
thyrotoxicosis
factitia.
Critical Results
N/A
Test Limitations
Therapy with amiodarone can lead to depressed T3 values.
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.
Autoantibodies to thyroid hormones can interfere with the
assay.
Binding protein anomalies seen with FDH (familial
dysalbuminemic
hyperthyroxinemia), for example, may cause values which, while
characteristic of the condition, deviate from the expected
results.
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 NTIb-patients,
pregnancy, use of oral contraceptives). In such cases a fT3 or
fT4
determination is indicated.
Results should always be assessed in conjunction with
patient’s medical history, clinical examination and other
findings.
Whole blood/unspun specimens greater than 6 hours will
be
rejected.
Additional Information
- Gel Separator tubes need to be spun within 2 hours of
collection and transported refrigerated (2 -
8˚C). - Minimum volume of 250µL of plasma
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Specimen |
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Specimen Type |
Container |
Additive |
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Serum Preferred |
Red Top |
None |
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Gold Top |
Gel separator | |
|
Plasma Acceptable |
Mint Green |
Li Heparin Gel separator |
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Dark Green |
Li Heparin | |
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Specimen |
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Specimen Type |
Storage |
Stability |
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Serum |
Room Temperature (15 - |
N/A |
|
Refrigerated (2 - |
7 Days |
|
|
Frozen (-20˚C) |
1 Month |
|
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Plasma |
Room Temperature (15 - |
N/A |
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Refrigerated (2 - |
7 Days |
|
|
Frozen (-20˚C) |
1 Month |
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Fee Code
30184480
Synonyms
T3, T3, TT3, Total T3
Specimen Minimum Volume
2 mL
DAY(S) AND TIME(S) PERFORMED
24 hours, 7 days a week including holidays.
STAT DAY(S) AND TIME(S) PERFORMED
N/A
CPT
84480
Method Name
Electrochemiluminescence immunoassay (ECLIA)
Reference Values
80 – 195 ng/dL