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Test Code LAB0208116 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

 

Diagnosing triiodothyronine (T3) toxicosis

 

This test is not useful for general screening of the population without clinical suspicion of hyperthyroidism.

Testing Algorithm

For information see Thyroid Function Ordering Algorithm.

Method Name

Electrochemiluminescence Immunoassay

Reporting Name

T3 (Triiodothyronine), Total, S

Specimen Type

Serum


Specimen Required


Collection Container/Tube:

Preferred: Serum gel

Acceptable: Red top

Submission Container/Tube: Plastic vial

Specimen Volume: 1 mL

Collection Instructions: Centrifuge and aliquot serum into plastic vial.


Specimen Minimum Volume

0.75 mL

Specimen Stability Information

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

Reject Due To

Gross hemolysis Reject
Gross lipemia OK
Gross icterus OK

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 www.mayocliniclabs.com/order-tests/si-unit-conversion.html

Interpretation

Triiodothyronine (T3) values above 200 ng/dL in adults or over 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) Performed

Monday through Saturday

Report Available

1 to 3 days

Specimen Retention Time

14 days

Test Classification

This test has been cleared, approved, or is exempt by the US 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 83124-8

 

Result ID Test Result Name Result LOINC Value
T3 T3 (Triiodothyronine), Total, S 83124-8