Banner Image

Test Directory

T3 Reverse, LC/MS/MS

Test Summary

3,3',5'-Triiodothyronine (reverse T3, rT3) is, along with 3,3,5'-Triiodothyronine (T3) a deiodinated metabolite of thyroxine (T4), the major secretory product of the thyroid gland and is secreted into the bloodstream. Unlike T3, however, rT3 is thought to be metabolically inert.
The process of 5'-monodeiodination that converts T4 to T3, and rT3 to diiodothyronine (DTT) is inhibited in a wide variety of conditions, collectively referred to as nonthyroidal illnesses (NTI) or the 'euthyroid sick' state. These conditions include fasting, malnutrition, poorly controlled diabetes mellitus, trauma, surgery, and systemic illness. Consequently, in patients with NTI the serum T3 level typically decreases, and the rT3 often, but not always, increases.

Aliases

  • Reverse T3
  • RT3

Specimen Collection

Special Instructions

N/A

Preferred Specimen

0.5 mL serum

Minimum Volume

0.3 mL

Instructions

Serum: Allow blood to clot at room temperature for 30 minutes. Centrifuge to separate serum from the cells within 24 hours of collection and immediately pour serum into a plastic transport tube.

Plasma: Centrifuge to separate plasma from the cells within 24 hours of collection and immediately pour plasma into a plastic transport tube.


Patient Preparation

N/A

Storage

Transport tube

Transport Temperature

Room temperature

Specimen Stability

  • Room temperature: 7 days
  • Refrigerated: 7 days
  • Frozen: 30 days

Limitations

N/A

Other Acceptable Specimens

Plasma collected in sodium heparin (green-top), or EDTA (lavender-top) tube

Unacceptable Specimens

Unseparated serum (>48 hours on clot) • Serum in Serum separator tube (SST) not separated from the gel within 24 hours

Order Code

T3REV

EPIC (Premier) Code

LAB5363

Includes

N/A

CPT Code

  • 84482

Billing Code

  • 700000

CPT Statement

Methodology

Chromatography/Mass Spectrometry

FDA Status

This test was developed and its analytical performance characteristics have been determined by Quest Diagnostics. It has not been cleared or approved by the U.S. Food and Drug Administration. The FDA has determined that such clearance or approval is not necessary. This assay has been validated pursuant to the CLIA regulations and is used for clinical purposes.

Physician Attestation of Informed Consent

N/A

Testing Laboratory

Quest Diagnostics Nichols Institute
14225 Newbrook Drive
Chantilly VA, 20153

Reference Range

8-25 ng/dL

Setup Schedule / Expected Turnaround Time

Daily; Report available: 2 - 4 days

Specimen Collection

Special Instructions

N/A

Preferred Specimen

0.5 mL serum

Minimum Volume

0.3 mL

Instructions

Serum: Allow blood to clot at room temperature for 30 minutes. Centrifuge to separate serum from the cells within 24 hours of collection and immediately pour serum into a plastic transport tube.

Plasma: Centrifuge to separate plasma from the cells within 24 hours of collection and immediately pour plasma into a plastic transport tube.


Patient Preparation

N/A

Storage

Transport tube

Transport Temperature

Room temperature

Specimen Stability

  • Room temperature: 7 days
  • Refrigerated: 7 days
  • Frozen: 30 days

Limitations

N/A

Other Acceptable Specimens

Plasma collected in sodium heparin (green-top), or EDTA (lavender-top) tube

Unacceptable Specimens

Unseparated serum (>48 hours on clot) • Serum in Serum separator tube (SST) not separated from the gel within 24 hours

Billing

CPT Code

  • 84482

Billing Code

  • 700000

CPT Statement

Result Information

Methodology

Chromatography/Mass Spectrometry

Testing Laboratory

N/A

Reference Range

8-25 ng/dL

Setup Schedule / Expected Turnaround Time

Daily; Report available: 2 - 4 days