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Test Code 0208116 T3 (Triiodothyronine), Total, Serum

Additional Codes

Mayo Test ID
T3

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Useful For

Second-order testing for hyperthyroidism in patients with low thyroid-stimulating hormone values and normal thyroxine levels

 

Diagnosis of triiodothyronine toxicosis

Testing Algorithm

See Thyroid Function Ordering Algorithm in Special Instructions.

Method Name

Electrochemiluminescence Immunoassay

Reporting Name

T3 (Triiodothyronine), Total, S

Specimen Type

Serum


Specimen Required


Patient Preparation: For 12 hours before this test do not take multivitamins or dietary supplements containing biotin (vitamin B7), which is commonly found in hair, skin, and nail supplements and multivitamins.

Container/Tube:

Preferred: Serum gel

Acceptable: Red top

Submission Container/Tube: Plastic vial

Specimen Volume: 1 mL


Specimen Minimum Volume

0.5 mL

Specimen Stability Information

Specimen Type Temperature Time
Serum Refrigerated (preferred) 7 days
  Frozen  30 days

Reject Due To

Hemolysis

Mild OK; Gross reject

Lipemia

Mild OK; Gross OK

Icterus

Mild OK; Gross OK

Other

NA

Reference Values

Pediatric

0-5 days: 73-288 ng/dL

6 days-2 months: 80-275 ng/dL

3-11 months: 86-265 ng/dL

1-5 years: 92-248 ng/dL

6-10 years: 93-231 ng/dL

11-19 years: 91-218 ng/dL

 

Adult (≥20 years): 80-200 ng/dL

 

For SI unit Reference Values, see https://www.mayocliniclabs.com/order-tests/si-unit-conversion.html

Interpretation

Triiodothyronine (T3) values >200 ng/dL in adults or > age related cutoffs in children are consistent with hyperthyroidism or increased thyroid hormone-binding proteins.

 

Abnormal levels (high or low) of thyroid hormone-binding proteins (primarily albumin and thyroid-binding globulin) may cause abnormal T3 concentrations in euthyroid patients.

Day(s) and Time(s) Performed

Monday through Friday; 5 a.m.-12 a.m.

Saturday; 6 a.m.-6 p.m.

Analytic Time

Same day/1 day

Specimen Retention Time

14 days

Test Classification

This test has been cleared or approved by the U.S. Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.

CPT Code Information

84480

LOINC Code Information

Test ID Test Order Name Order LOINC Value
T3 T3 (Triiodothyronine), Total, S 3053-6

 

Result ID Test Result Name Result LOINC Value
T3 T3 (Triiodothyronine), Total, S 3053-6