T 3 Reverse, LC/MS/MS

Test Code

T3RVE

Alias/See Also

LAB9721

CPT Codes
<p>84482</p>

Preferred Specimen

Specimen Type: Serum

Collection Container/Type

Preferred: Serum gel

Acceptable: Red top

Submission Container/Tube: Plastic vial

Specimen Volume: 0.5 mL

Collection Instructions:

Allow blood to clot at room temperature for 30 minutes.

Centrifuge and separate the serum from cells immediately.

Alternatively, collect blood in a serum separator tube (SST), allow to clot at room temperature, centrifuge, and remove from gel within 24 hours.

Specimen Type: Plasma

Collection Container/Type

Preferred: Green top (Sodium heparin)

Acceptable: Lavender top (EDTA)

Submission Container/Tube: Plastic vial

Specimen Volume: 0.5 mL

Minimum Volume

0.3 mL

Other Acceptable Specimens

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

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.

Transport Container

Transport tube

Transport Temperature

Room temperature

Specimen Stability

Room temperature: 7 days

Refrigerated: 7 days

Frozen: 30 days

Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)

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

Methodology

Chromatography/Mass Spectrometry

This test was developed and its analytical performance characteristics have been determined by Quest Diagnostics. It has not been cleared or approved by FDA. This assay has been validated pursuant to the CLIA regulations and is used for clinical purposes.

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 FDA. This assay has been validated pursuant to the CLIA regulations and is used for clinical purposes.

Setup Schedule

Set up: Daily; Report available: 2-4 days

Report Available

2-4 days

Reference Range

8-25 ng/dL

Clinical Significance

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.

Performing Laboratory
Quest Diagnostics Nichols Institute 14225 Newbrook Drive Chantilly, VA 20153

Last Updated: February 17, 2023

The CPT Codes provided in this document are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed. Any Profile/panel component may be ordered separately. Reflex tests are performed at an additional charge.