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Test Code T3C T3 Total (TRIIODOTHYRONINE)

Important Note

This test may be affected by biotin interference. Patients on high dose biotin (5mg/day or more) should not have samples drawn until at least 24 hours after the last biotin administration

Specimen and Container/Tube

Specimen Type: Serum

Preferred Specimen: Red Top

Other Acceptable specimens: Serum/Gold Top, Plasma/Li-Heparin Mint Green Top, Plasma/Lavendar K2 Top, Plasma/Lavendar K3 Top

Specimen Handling and Transport Instructions

UCMC Onsite Instructions: 

Collect specimen per standard collection procedure and send to laboratory immediately. 

 

UCMC Offsite and UC MedLab Outreach Instructions: 

  • Samples should be centrifuged within 2 hours of collection.
  • Centrifuge specimens at >2500 x g for 10 minutes at room temperature.
  • Aliquot sample into plastic transport tube containing a minimum of 0.2 mL of specimen.
  • Samples must be sent room temperature at 15-25oC.

Rejection Criteria

  • Common specimen rejected situations include: incorrect specimen type, insufficient volume, missing or incomplete specimen identifiers, incorrect specimen transport, or specimens outside stability limits. 
  • Specimens that are clotted or grossly hemolyzed.
  • Specimens that were transported unspun/whole blood and draw time is greater than 6 hours.

Reference Values

 

Test

Age

Sex

Reference Range

T3

All

All

80-195 ng/dL

Critical Values

Analyte

Unit

Low

High

Age

N/A

N/A

N/A

N/A

N/A

CPT Codes

84480

LOINC Codes

3053-6

Volume

Preferred Volume: 0.5 mL

Minimum Volume: 0.2 mL

Specimen Stability

Storage Temperature

Stability

Room temperature

8 days

Refrigerated

14 days

Frozen

12 months

Collection Instructions

Collect specimen per standard laboratory collection procedures. 

 

Test Components

T3 Total (TRIIODOTHYRONINE)

Clinical Indications

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.

Methodology

Electrochemiluminescence immunoassay (ECLIA)

Additional Information

  • Results should always be assessed in conjunction with patient's medical history, clinical examination and other findings.
  • 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.

Turnaround Time

Turnaround times are relative to the time the specimen is received in the test laboratory. 

 

STAT Turnaround Time: Not Available as STAT test

Routine Turnaround Time: 4 hours

Testing Schedule: 24/7

Synonyms/Keyword Search

T3, T3, TT3, Total T3

Last Review Date

7/31/24