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New England · Reverse T3 Test – rT3 Testing

Reverse T3 Test – rT3 Testing in Connecticut

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 Connecticut

Here is what you need before ordering and completing the Reverse T3 Test – rT3 Testing in CT. 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 Connecticut communities

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

Bridgeport975,078Reverse T3 Test – rT3 TestingHartford907,046Reverse T3 Test – rT3 TestingNew Haven587,648Reverse T3 Test – rT3 TestingNorwich201,726Reverse T3 Test – rT3 TestingWaterbury199,552Reverse T3 Test – rT3 TestingDanbury177,722Reverse T3 Test – rT3 TestingStamford134,820Reverse T3 Test – rT3 TestingNorwalk90,821Reverse T3 Test – rT3 TestingNew Britain74,022Reverse T3 Test – rT3 TestingMeriden60,790Reverse T3 Test – rT3 TestingBristol60,733Reverse T3 Test – rT3 TestingWest Haven55,518Reverse T3 Test – rT3 TestingMilford city 50,694Reverse T3 Test – rT3 TestingMiddletown47,164Reverse T3 Test – rT3 TestingShelton40,944Reverse T3 Test – rT3 TestingTorrington35,447Reverse T3 Test – rT3 TestingNaugatuck31,586Reverse T3 Test – rT3 TestingNew London27,585Reverse T3 Test – rT3 TestingWallingford Center19,211Reverse T3 Test – rT3 TestingAnsonia18,945Reverse T3 Test – rT3 TestingWillimantic18,150Reverse T3 Test – rT3 TestingStorrs16,784Reverse T3 Test – rT3 TestingDerby12,387Reverse T3 Test – rT3 TestingTrumbull Center10,468Reverse T3 Test – rT3 TestingKensington9,626Reverse T3 Test – rT3 TestingOakville9,507Reverse T3 Test – rT3 TestingConning Towers Nautilus Park9,479Reverse T3 Test – rT3 TestingSandy Hook9,406Reverse T3 Test – rT3 TestingRiverside9,133Reverse T3 Test – rT3 TestingLong Hill8,307Reverse T3 Test – rT3 TestingGlastonbury Center8,187Reverse T3 Test – rT3 TestingThompsonville8,134Reverse T3 Test – rT3 TestingSouthwood Acres7,875Reverse T3 Test – rT3 TestingRockville7,612Reverse T3 Test – rT3 TestingNew Canaan7,399Reverse T3 Test – rT3 TestingStaples7,125Reverse T3 Test – rT3 TestingCos Cob7,089Reverse T3 Test – rT3 TestingOld Greenwich6,929Reverse T3 Test – rT3 TestingWinsted6,662Reverse T3 Test – rT3 TestingNorthford6,117Reverse T3 Test – rT3 TestingSimsbury Center6,072Reverse T3 Test – rT3 TestingHazardville6,070Reverse T3 Test – rT3 TestingCheshire Village6,006Reverse T3 Test – rT3 TestingBranford Center5,934Reverse T3 Test – rT3 TestingDaniels Farm5,764Reverse T3 Test – rT3 TestingSherwood Manor5,710Reverse T3 Test – rT3 TestingNoroton5,682Reverse T3 Test – rT3 TestingPawcatuck5,383Reverse T3 Test – rT3 TestingLake Pocotopaug5,124Reverse T3 Test – rT3 TestingTerryville5,110Reverse T3 Test – rT3 TestingByram4,994Reverse T3 Test – rT3 TestingLong Hill4,645Reverse T3 Test – rT3 TestingQuinnipiac University4,614Reverse T3 Test – rT3 TestingStafford Springs4,611Reverse T3 Test – rT3 TestingMystic4,354Reverse T3 Test – rT3 TestingEast Village4,250Reverse T3 Test – rT3 TestingHeritage Village4,232Reverse T3 Test – rT3 TestingDanielson4,146Reverse T3 Test – rT3 TestingBroad Brook4,145Reverse T3 Test – rT3 TestingOronoque3,790Reverse T3 Test – rT3 Testing