Home
HelpTest Code LAB0232355 T3 (Triiodothyronine), Reverse, Serum
Additional Codes
| Mayo Test ID |
|---|
| RT3 |
Performing Laboratory
Mayo Clinic Laboratories in Rochester
Useful For
Aiding in the diagnosis of the sick euthyroid syndrome
Method Name
Liquid Chromatography Tandem Mass Spectrometry (LC-MS/MS)
Portions of this test are covered by patents held by Quest Diagnostics.
Reporting Name
T3 (Triiodothyronine), Reverse, SSpecimen Type
SerumSpecimen Required
Supplies: Sarstedt Aliquot Tube, 5 mL (T914)
Collection Container/Tube:
Preferred: Red top
Acceptable: Serum gel
Submission Container/Tube: Plastic vial
Specimen Volume: 0.8 mL
Collection Instructions: Centrifuge and aliquot serum into a plastic vial.
Specimen Minimum Volume
0.4 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Serum | Refrigerated (preferred) | 28 days | |
| Ambient | 28 days | ||
| Frozen | 28 days |
Reject Due To
| Gross hemolysis | Reject |
| Gross lipemia | OK |
| Gross icterus | OK |
Reference Values
10-24 ng/dL
Interpretation
In hospitalized or sick patients with low triiodothyronine (T3) values, elevated reverse triiodothyronine (rT3) values are consistent with sick euthyroid syndrome. Also, the finding on an elevated rT3 level in a critically ill patient helps exclude a diagnosis of hypothyroidism.
The rT3 is high in patients on medications such as propylthiouracil, ipodate, propranolol, amiodarone, dexamethasone, and the anesthetic agent halothane. Dilantin decreases rT3 due to the displacement from thyroxine-binding globulin, which causes increased rT3 clearance.
To convert from ng/dL to nmol/L, multiply the ng/dL result by 0.01536.
Day(s) Performed
Monday through Friday
Report Available
2 to 6 daysSpecimen Retention Time
14 daysTest Classification
This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.CPT Code Information
84482
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 |
Forms
If not ordering electronically, complete, print, and send a General Request (T239) with the specimen.