-1651085832.png){kind=logo}
Home
HelpTest Code RT3 T3 (Triiodothyronine), Reverse, Serum
Additional Codes
CNE Order Code: T3 Reverse
Reporting Name
T3 (Triiodothyronine), Reverse, SUseful For
Aiding in the diagnosis of the sick euthyroid syndrome
Performing Laboratory
Mayo Clinic Laboratories in Rochester
Specimen 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 |
Reference Values
10-24 ng/dL
Day(s) Performed
Monday through Friday
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 |
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.
Report Available
2 to 6 daysReject Due To
| Gross hemolysis | Reject |
| Gross lipemia | OK |
| Gross icterus | OK |
Method Name
Liquid Chromatography Tandem Mass Spectrometry (LC-MS/MS)
Portions of this test are covered by patents held by Quest Diagnostics.
Forms
If not ordering electronically, complete, print, and send a General Request (T239) with the specimen.