Lab test requirements · preparation, ID, referral, and timing United States · 0 communities
LabRequirements Know what your test requires

South · Reverse T3 Test – rT3 Testing

Reverse T3 Test – rT3 Testing in Texas

This page explains the reverse t3 test – rt3 testing, what it measures, and how to order it. The Reverse T3 blood test measures a form of thyroid hormone that can help clarify unusual thyroid function test results. It is often used alongside other thyroid tests to give a fuller picture of how the body is handling thyroid hormone.

Sample typeBlood and/or urine at a collection lab
ReferralIncluded — no referral from your own doctor needed

Lab requirements in Texas

Here is what you need before ordering and completing the Reverse T3 Test – rT3 Testing in TX. Review each item and confirm the details with the collection lab.

Physician's order
Included. A physician's order is required for lab testing and is provided for you by our partner's physicians — no referral from your own doctor is needed.
Fasting
Some tests require fasting or avoiding certain foods or drinks beforehand. You will be informed when you order — confirm the details with the collection lab.
Preparation
Preparation instructions can vary depending on the laboratory and the other tests being performed at the same time. Always follow the specific instructions provided by the collection lab or…
Sample & visit
A blood and/or urine sample is collected; the visit usually takes about 10 minutes.
Identification
Bring the lab requisition form from your account. The collection lab may also ask for a government-issued photo ID.
Turnaround
1-3 business days
Availability
Our partner lab does not serve ND, RI, NY, NJ, MD or HI. Confirm availability for your location with the collection lab.

Before you go

  • Order your test before visiting a lab, then use the requisition form in your account.
  • Print the requisition form, or fax it to the lab directly from your account.
  • No scheduling is needed — visit the collection lab during its normal business hours.
  • A blood and/or urine sample is collected; the visit usually takes about 10 minutes.
  • Bring a government-issued photo ID in case the lab requests it.
  • Results are posted to your secure account within 1–3 business days.

Requirements are summarized from our partner lab's published policies. Preparation and availability can change — confirm current instructions with the collection lab before your visit.

What this test is

Reverse T3 is a biologically inactive form of thyroid hormone produced when the body converts thyroxine (T4) in an alternative pathway. This test measures the amount of reverse T3 circulating in the blood. It is not a stand-alone diagnostic test but is interpreted with other thyroid hormone measurements.

What it measures

  • Reverse T3 — reflects the amount of this inactive thyroid hormone form in the blood
  • Total T3 — often measured alongside to assess active thyroid hormone levels
  • Free T4 — helps evaluate the main thyroid hormone produced by the thyroid gland
  • TSH — indicates how the pituitary gland is responding to thyroid hormone levels

What the test involves

A healthcare professional collects a small sample of blood, usually from a vein in your arm, using a standard blood draw. The sample is then sent to a laboratory for analysis.

Why it is often ordered

A clinician may order a reverse T3 test when thyroid test results are confusing or when a nonthyroidal illness is suspected. It is typically used to help evaluate whether symptoms or abnormal thyroid tests might be related to how the body is converting thyroid hormones.

Preparation

Preparation instructions can vary depending on the laboratory and the other tests being performed at the same time. Always follow the specific instructions provided by the collection lab or your healthcare provider.

How results are reported

Results are reported as a numeric value for reverse T3, and the laboratory will provide a reference range for comparison. Reference ranges can differ between laboratories because of differences in equipment, methods, and population, so your result should be interpreted using the range from the lab that performed the test.

Before you go

  • Whether any other tests will be drawn at the same time and if fasting is required.
  • The specific reference range used by the laboratory performing the test.
  • How and when you will receive your results.

Cities

Reverse T3 Test – rT3 Testing in Texas communities

Choose your city for local context and to order this test.

Dallas5,668,165Reverse T3 Test – rT3 TestingHouston5,650,910Reverse T3 Test – rT3 TestingSan Antonio1,910,785Reverse T3 Test – rT3 TestingAustin1,659,251Reverse T3 Test – rT3 TestingFort Worth908,469Reverse T3 Test – rT3 TestingMcAllen809,002Reverse T3 Test – rT3 TestingEl Paso794,344Reverse T3 Test – rT3 TestingDenton445,814Reverse T3 Test – rT3 TestingArlington392,304Reverse T3 Test – rT3 TestingCorpus Christi333,764Reverse T3 Test – rT3 TestingThe Woodlands292,380Reverse T3 Test – rT3 TestingPlano282,181Reverse T3 Test – rT3 TestingLubbock259,946Reverse T3 Test – rT3 TestingLaredo256,748Reverse T3 Test – rT3 TestingIrving254,184Reverse T3 Test – rT3 TestingMcKinney248,840Reverse T3 Test – rT3 TestingGarland245,075Reverse T3 Test – rT3 TestingKilleen238,288Reverse T3 Test – rT3 TestingBrownsville235,735Reverse T3 Test – rT3 TestingCollege Station207,514Reverse T3 Test – rT3 TestingAmarillo204,357Reverse T3 Test – rT3 TestingGrand Prairie195,992Reverse T3 Test – rT3 TestingFrisco193,140Reverse T3 Test – rT3 TestingWaco187,172Reverse T3 Test – rT3 TestingPort Arthur156,988Reverse T3 Test – rT3 TestingPasadena151,964Reverse T3 Test – rT3 TestingMesquite149,848Reverse T3 Test – rT3 TestingHarlingen148,545Reverse T3 Test – rT3 TestingTyler143,895Reverse T3 Test – rT3 TestingBeaumont137,549Reverse T3 Test – rT3 TestingOdessa134,793Reverse T3 Test – rT3 TestingCarrollton131,388Reverse T3 Test – rT3 TestingMidland130,765Reverse T3 Test – rT3 TestingAbilene125,474Reverse T3 Test – rT3 TestingPearland122,609Reverse T3 Test – rT3 TestingTexas City122,017Reverse T3 Test – rT3 TestingRound Rock117,735Reverse T3 Test – rT3 TestingRichardson115,904Reverse T3 Test – rT3 TestingTemple115,809Reverse T3 Test – rT3 TestingLeague City111,847Reverse T3 Test – rT3 TestingSugar Land110,272Reverse T3 Test – rT3 TestingLewisville110,077Reverse T3 Test – rT3 TestingAllen102,778Reverse T3 Test – rT3 TestingWichita Falls102,563Reverse T3 Test – rT3 TestingSan Angelo100,330Reverse T3 Test – rT3 TestingEdinburg98,759Reverse T3 Test – rT3 TestingLongview98,075Reverse T3 Test – rT3 TestingConroe87,930Reverse T3 Test – rT3 TestingNew Braunfels87,549Reverse T3 Test – rT3 TestingMission85,311Reverse T3 Test – rT3 TestingBryan85,204Reverse T3 Test – rT3 TestingAtascocita84,222Reverse T3 Test – rT3 TestingBaytown82,543Reverse T3 Test – rT3 TestingTexarkana79,304Reverse T3 Test – rT3 TestingPharr78,997Reverse T3 Test – rT3 TestingFlower Mound75,050Reverse T3 Test – rT3 TestingCedar Park74,741Reverse T3 Test – rT3 TestingMissouri City73,682Reverse T3 Test – rT3 TestingLake Jackson73,478Reverse T3 Test – rT3 TestingMansfield71,375Reverse T3 Test – rT3 Testing