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Test Code RT3 T3 (Triiodothyronine), Reverse, Serum

Reporting Name

T3 (Triiodothyronine), Reverse, S

Useful For

An aid in the diagnosis of the "sick euthyroid" syndrome

Performing Laboratory

Mayo Medical Laboratories in Rochester

Specimen Type


Specimen Required

Collection Container/Tube:

Preferred: Red top

Acceptable: Serum gel

Submission Container/Tube: Plastic vial

Specimen Volume: 0.8 mL

Specimen Minimum Volume

0.4 mL

Specimen Stability Information

Specimen Type Temperature Time
Serum Refrigerated (preferred) 28 days
  Ambient  28 days
  Frozen  28 days

Reference Values

10-24 ng/dL

Day(s) and Time(s) Performed

Monday, Wednesday, Thursday, Friday; 9 a.m.

Test Classification

This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the U.S. Food and Drug Administration.

CPT Code Information


LOINC Code Information

Test ID Test Order Name Order LOINC Value
RT3 T3 (Triiodothyronine), Reverse, S 3052-8


Result ID Test Result Name Result LOINC Value
9405 T3(Triiodothyronine),Reverse,S 3052-8

Reject Due To



Mild OK; Gross reject


Mild OK; Gross OK


Mild OK; Gross OK



Method Name

Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)

Portions of this test are covered by patents held by Quest Diagnostics.


If not ordering electronically, complete, print, and send a General Request Form (T239) with the specimen (