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Test Code T3C T3-Triiodothyronine, Total, Serum

Important Note

Patients on high does biotin (>5mg/day) should not have samples drawn until at least 8 hours after the last biotin administration.

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

 

Specimen
Container

Specimen Type

Container

Additive

Serum Preferred

Red Top

None

Gold Top

Gel separator

Plasma Acceptable

Mint Green

Li Heparin Gel
separator

Dark Green

Li Heparin

Specimen
Stability

Specimen Type

Storage
Temperature

Stability

Serum

Room Temperature  (15 -
25˚C)

N/A

Refrigerated  (2 -
8˚C)

7 Days

Frozen  (-20˚C)

1 Month

Plasma

Room Temperature  (15 -
25˚C)

N/A

Refrigerated  (2 -
8˚C)

7 Days

Frozen  (-20˚C)

1 Month

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