Lab test requirements · preparation, ID, referral, and timing United States · 15,280 communities
LabRequirements Know what your test requires

Southwest · Reverse T3 Test – rT3 Testing

Reverse T3 Test – rT3 Testing in Arizona

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 Arizona

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

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

Phoenix4,047,095Reverse T3 Test – rT3 TestingTucson875,284Reverse T3 Test – rT3 TestingMesa497,752Reverse T3 Test – rT3 TestingChandler272,439Reverse T3 Test – rT3 TestingGilbert262,249Reverse T3 Test – rT3 TestingAvondale254,537Reverse T3 Test – rT3 TestingGlendale245,685Reverse T3 Test – rT3 TestingScottsdale238,685Reverse T3 Test – rT3 TestingPeoria187,733Reverse T3 Test – rT3 TestingTempe178,862Reverse T3 Test – rT3 TestingSurprise141,875Reverse T3 Test – rT3 TestingYuma135,933Reverse T3 Test – rT3 TestingPrescott Valley97,901Reverse T3 Test – rT3 TestingSan Tan Valley96,127Reverse T3 Test – rT3 TestingGoodyear93,651Reverse T3 Test – rT3 TestingBuckeye89,711Reverse T3 Test – rT3 TestingFlagstaff81,682Reverse T3 Test – rT3 TestingCasas Adobes70,224Reverse T3 Test – rT3 TestingQueen Creek57,728Reverse T3 Test – rT3 TestingMaricopa57,075Reverse T3 Test – rT3 TestingLake Havasu City56,510Reverse T3 Test – rT3 TestingCasa Grande53,488Reverse T3 Test – rT3 TestingMarana50,834Reverse T3 Test – rT3 TestingCatalina Foothills50,096Reverse T3 Test – rT3 TestingOro Valley46,515Reverse T3 Test – rT3 TestingPrescott45,063Reverse T3 Test – rT3 TestingSierra Vista44,944Reverse T3 Test – rT3 TestingBullhead City41,064Reverse T3 Test – rT3 TestingApache Junction38,311Reverse T3 Test – rT3 TestingSun City37,693Reverse T3 Test – rT3 TestingEl Mirage35,410Reverse T3 Test – rT3 TestingSan Luis35,289Reverse T3 Test – rT3 TestingSahuarita33,524Reverse T3 Test – rT3 TestingKingman32,204Reverse T3 Test – rT3 TestingDrexel Heights30,599Reverse T3 Test – rT3 TestingFortuna Foothills26,727Reverse T3 Test – rT3 TestingSun City West26,354Reverse T3 Test – rT3 TestingFlorence25,356Reverse T3 Test – rT3 TestingFountain Hills23,639Reverse T3 Test – rT3 TestingAnthem22,750Reverse T3 Test – rT3 TestingRio Rico20,914Reverse T3 Test – rT3 TestingGreen Valley20,729Reverse T3 Test – rT3 TestingNogales19,829Reverse T3 Test – rT3 TestingNew River17,731Reverse T3 Test – rT3 TestingFlowing Wells16,965Reverse T3 Test – rT3 TestingDouglas16,470Reverse T3 Test – rT3 TestingPayson16,229Reverse T3 Test – rT3 TestingFort Mohave15,872Reverse T3 Test – rT3 TestingEloy15,171Reverse T3 Test – rT3 TestingTanque Verde14,946Reverse T3 Test – rT3 TestingSierra Vista Southeast14,822Reverse T3 Test – rT3 TestingVail14,715Reverse T3 Test – rT3 TestingSomerton14,126Reverse T3 Test – rT3 TestingSun Lakes13,912Reverse T3 Test – rT3 TestingCoolidge13,347Reverse T3 Test – rT3 TestingValencia West12,887Reverse T3 Test – rT3 TestingNew Kingman-Butler12,858Reverse T3 Test – rT3 TestingChino Valley12,854Reverse T3 Test – rT3 TestingParadise Valley12,666Reverse T3 Test – rT3 TestingVerde Village12,658Reverse T3 Test – rT3 Testing