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Test Code TT3 / T3C T3 Total (TRIIODOTHYRONINE)

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

Serum

Container/Tube

Red Top

Offsite Collection Instructions

1. Collect sample following standard collection methods
2. Within 2 hours of collection the sample must be spun and
aliquoted
3. Transport refrigerated  (2 – 8C).

Test Includes

N/A

Preferred Volume

0.5 mL

Specimen Minimum Volume

0.2 mL

Reject Due To

Whole blood/unspun samples greater than 6 hours will be
rejected.

DAY(S) AND TIME(S) PERFORMED

24 hours, 7 days a week including holidays.

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.

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.

UCMC Collection Instructions

1. Collect sample following standard collection methods
2. Within 2 hours of collection the sample must be received in
Laboratory Service Center
3. Transport room temperature (15 – 25C).

Critical Results

N/A

Additional Information

N/A

Included in Additional codes

N/A

Coverage Information

N/A

Stability: Room Temp

n/a

Stability: Refrigerated

7 days

Stability: Frozen

1 month

Reference Values

80 – 195 ng/dL