Clinics and Departments

Laboratory Services

Lab Dept:

Chemistry

Test Name:

T3 (TRIIODOTHYRONINE) TOTAL, SERUM

General Information

Lab Order Codes:

TT3

Synonyms:

T3 RIA, T3R, Total T3, T3

CPT Codes:

84480 – Triiodothyronine T3; total (TT-3)

Test Includes:

T3 concentration reported in ng/mL.

Logistics

Test Indications:

T3 (Triiodothyronine) is produced by the thyroid and secreted in response to TSH. T3 is physiologically more potent than T4. 99.7% of t3 is bound to protein and acts as a reserve for the metabolically active free T3. T3 blood levels are useful in assessing hyperthyroidism.

Lab Testing Sections:

Chemistry (all testing is performed on the St. Paul campus)

Phone Numbers:

MIN Lab: 612-813-6280

STP Lab: 651-220-6550

Test Availability:

Daily, 24 hours

Turnaround Time:

1 – 3 days, test performed Monday – Friday.

Special Instructions:

N/A

Specimen

Specimen Type:

Blood

Container:

Red top (plain, no gel) tube

Draw Volume:

1.5 mL (Minimum: 0.6 mL) blood

Processed Volume:

0.5 mL (Minimum: 0.2 mL) serum

Collection:

Routine venipuncture

Special Processing:

Lab Staff: Centrifuge specimen, remove serum aliquot into a plastic sample cup. Store at refrigerated temperatures.

Patient Preparation:

None

Sample Rejection:

Mislabeled or unlabeled specimen; specimens other than serum; gross hemolysis

Interpretive

Reference Range:

Age:

Range (ng/mL):

0 - 6 days:

0.89 - 4.05 ng/mL

7 days - 1 month:

0.91 - 3.00 ng/mL

1 month - 1 year:

0.85 - 2.50 ng/mL

1 - 10 years:

1.19 - 2.18 ng/mL

>10 years:

0.55 - 1.70 ng/mL

Critical Values:

N/A

Limitations:

Heterophile antibodies may interfere with immunoassay testing.

Methodology:

Competitive Immunoassay/Chemiluminescence

References:

Diagnostic Products Corporation T3 Package Insert PIL2KT3-17 (07/29/2008)



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