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24907 T3 Reverse (RT3)

T3 Reverse (RT3)
Test Code: T3RSO
Synonyms/Keywords
Triiodothyronine, Reverse
Useful For
A​ids in the diagnosis of the "sick euthyroid" syndrome
Specimen Requirements
Fasting Required Specimen Type Preferred Container/Tube Acceptable Container/Tube Specimen Volume Specimen Minimum Volume
(allows for 1 repeat)		 Pediatric Minimum Volume
(no repeat)
No​ ​Serum ​Red Top Tube (RTT) ​Serum Separator Tube (SST) ​0.8 mL ​0.4 mL ​
Specimen Stability Information
Specimen Type Temperature Time
​Serum ​ ​ Refrigerate (preferred) 28 days
​Ambient 28 days
Frozen ​28 days
Rejection Criteria
Samples that are grossly hemolyzed
Performing Laboratory Information
Performing Location Day(s) Test Performed Analytical Time Methodology/Instrumentation
Mayo Medical Laboratories​ Monday, Wednesday, Thursday, Friday​ ​2 days ​LC-MS/MS
Test Information
Test aids in the diagnosis of the “sick euthyroid syndrome". Generally, reverse triiodothyronine tests are not necessary since triiodothyronine should not be ordered in hospitalized or sick patients.
Reference Range Information
Performing Location Reference Range
​Mayo Medical Laboratories ​10-24 ng/dL
Outreach CPTs
CPT Modifier
(if needed)		 Quantity Description Comments
​84482 ​ ​ ​ ​
Synonyms/Keywords
Triiodothyronine, Reverse
Ordering Applications
Ordering Application Description
If the ordering application you are looking for is not listed, contact your local laboratory for assistance.
Specimen Requirements
Fasting Required Specimen Type Preferred Container/Tube Acceptable Container/Tube Specimen Volume Specimen Minimum Volume
(allows for 1 repeat)		 Pediatric Minimum Volume
(no repeat)
No​ ​Serum ​Red Top Tube (RTT) ​Serum Separator Tube (SST) ​0.8 mL ​0.4 mL ​
Specimen Stability Information
Specimen Type Temperature Time
​Serum ​ ​ Refrigerate (preferred) 28 days
​Ambient 28 days
Frozen ​28 days
Rejection Criteria
Samples that are grossly hemolyzed
Useful For
A​ids in the diagnosis of the "sick euthyroid" syndrome
Reference Range Information
Performing Location Reference Range
​Mayo Medical Laboratories ​10-24 ng/dL
For more information visit:
Performing Laboratory Information
Performing Location Day(s) Test Performed Analytical Time Methodology/Instrumentation
Mayo Medical Laboratories​ Monday, Wednesday, Thursday, Friday​ ​2 days ​LC-MS/MS
For billing questions, see Contacts
Outreach CPTs
CPT Modifier
(if needed)		 Quantity Description Comments
​84482 ​ ​ ​ ​
For most current information refer to the Marshfield Laboratory online reference manual.