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Mountain West · Reverse T3 Test – rT3 Testing

Reverse T3 Test – rT3 Testing in Colorado

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 Colorado

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

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

Denver2,650,725Reverse T3 Test – rT3 TestingColorado Springs628,808Reverse T3 Test – rT3 TestingAurora383,496Reverse T3 Test – rT3 TestingFort Collins301,596Reverse T3 Test – rT3 TestingLakewood155,608Reverse T3 Test – rT3 TestingPueblo142,727Reverse T3 Test – rT3 TestingThornton140,538Reverse T3 Test – rT3 TestingGreeley135,270Reverse T3 Test – rT3 TestingGrand Junction134,074Reverse T3 Test – rT3 TestingArvada122,903Reverse T3 Test – rT3 TestingBoulder120,818Reverse T3 Test – rT3 TestingWestminster115,535Reverse T3 Test – rT3 TestingCentennial107,972Reverse T3 Test – rT3 TestingLongmont104,035Reverse T3 Test – rT3 TestingHighlands Ranch103,238Reverse T3 Test – rT3 TestingLafayette99,475Reverse T3 Test – rT3 TestingLoveland75,938Reverse T3 Test – rT3 TestingBroomfield72,697Reverse T3 Test – rT3 TestingCastle Rock71,037Reverse T3 Test – rT3 TestingCommerce City61,516Reverse T3 Test – rT3 TestingParker57,311Reverse T3 Test – rT3 TestingLittleton45,465Reverse T3 Test – rT3 TestingSecurity-Widefield40,158Reverse T3 Test – rT3 TestingBrighton39,895Reverse T3 Test – rT3 TestingNorthglenn37,899Reverse T3 Test – rT3 TestingDakota Ridge34,361Reverse T3 Test – rT3 TestingKen Caryl33,889Reverse T3 Test – rT3 TestingEnglewood33,500Reverse T3 Test – rT3 TestingPueblo West32,991Reverse T3 Test – rT3 TestingWheat Ridge32,340Reverse T3 Test – rT3 TestingWindsor31,972Reverse T3 Test – rT3 TestingFountain29,495Reverse T3 Test – rT3 TestingErie29,367Reverse T3 Test – rT3 TestingColumbine25,924Reverse T3 Test – rT3 TestingEvans21,727Reverse T3 Test – rT3 TestingFour Square Mile21,723Reverse T3 Test – rT3 TestingLouisville21,091Reverse T3 Test – rT3 TestingClifton20,122Reverse T3 Test – rT3 TestingMontrose20,098Reverse T3 Test – rT3 TestingSherrelwood20,069Reverse T3 Test – rT3 TestingGolden20,041Reverse T3 Test – rT3 TestingDurango18,953Reverse T3 Test – rT3 TestingCimarron Hills18,619Reverse T3 Test – rT3 TestingCañon City17,157Reverse T3 Test – rT3 TestingFort Carson16,743Reverse T3 Test – rT3 TestingJohnstown16,596Reverse T3 Test – rT3 TestingWelby16,260Reverse T3 Test – rT3 TestingFirestone15,949Reverse T3 Test – rT3 TestingGreenwood Village15,548Reverse T3 Test – rT3 TestingBlack Forest14,375Reverse T3 Test – rT3 TestingFrederick14,127Reverse T3 Test – rT3 TestingFederal Heights14,111Reverse T3 Test – rT3 TestingSterling13,976Reverse T3 Test – rT3 TestingLone Tree13,701Reverse T3 Test – rT3 TestingFruita13,296Reverse T3 Test – rT3 TestingSuperior13,283Reverse T3 Test – rT3 TestingSteamboat Springs13,193Reverse T3 Test – rT3 TestingFort Morgan11,483Reverse T3 Test – rT3 TestingCherry Creek11,389Reverse T3 Test – rT3 TestingCastle Pines11,296Reverse T3 Test – rT3 Testing