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Mountain West · Reverse T3 Test – rT3 Testing

Reverse T3 Test – rT3 Testing in Idaho

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 Idaho

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

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

Boise422,665Reverse T3 Test – rT3 TestingNampa194,547Reverse T3 Test – rT3 TestingMeridian115,227Reverse T3 Test – rT3 TestingCoeur d'Alene114,880Reverse T3 Test – rT3 TestingIdaho Falls101,326Reverse T3 Test – rT3 TestingPocatello74,359Reverse T3 Test – rT3 TestingCaldwell58,872Reverse T3 Test – rT3 TestingTwin Falls51,223Reverse T3 Test – rT3 TestingPost Falls38,162Reverse T3 Test – rT3 TestingLewiston33,964Reverse T3 Test – rT3 TestingRexburg33,684Reverse T3 Test – rT3 TestingEagle29,665Reverse T3 Test – rT3 TestingMoscow25,336Reverse T3 Test – rT3 TestingKuna23,765Reverse T3 Test – rT3 TestingAmmon17,401Reverse T3 Test – rT3 TestingMountain Home15,863Reverse T3 Test – rT3 TestingChubbuck15,445Reverse T3 Test – rT3 TestingHayden15,316Reverse T3 Test – rT3 TestingJerome12,182Reverse T3 Test – rT3 TestingBlackfoot12,106Reverse T3 Test – rT3 TestingGarden City12,056Reverse T3 Test – rT3 TestingBurley11,274Reverse T3 Test – rT3 TestingStar10,929Reverse T3 Test – rT3 TestingRathdrum9,099Reverse T3 Test – rT3 TestingMiddleton9,091Reverse T3 Test – rT3 TestingHailey9,001Reverse T3 Test – rT3 TestingSandpoint8,448Reverse T3 Test – rT3 TestingPayette7,999Reverse T3 Test – rT3 TestingEmmett7,408Reverse T3 Test – rT3 TestingRupert5,994Reverse T3 Test – rT3 TestingFruitland5,903Reverse T3 Test – rT3 TestingWeiser5,578Reverse T3 Test – rT3 TestingPreston5,545Reverse T3 Test – rT3 TestingRigby4,920Reverse T3 Test – rT3 TestingShelley4,784Reverse T3 Test – rT3 TestingBuhl4,532Reverse T3 Test – rT3 TestingAmerican Falls4,531Reverse T3 Test – rT3 TestingKimberly4,508Reverse T3 Test – rT3 TestingLincoln3,919Reverse T3 Test – rT3 TestingSt. Anthony3,677Reverse T3 Test – rT3 TestingGooding3,625Reverse T3 Test – rT3 TestingHeyburn3,592Reverse T3 Test – rT3 TestingMcCall3,568Reverse T3 Test – rT3 TestingKetchum3,448Reverse T3 Test – rT3 TestingHidden Springs3,382Reverse T3 Test – rT3 TestingVictor3,315Reverse T3 Test – rT3 TestingGrangeville3,296Reverse T3 Test – rT3 TestingOrofino3,216Reverse T3 Test – rT3 TestingSalmon3,114Reverse T3 Test – rT3 TestingSoda Springs3,084Reverse T3 Test – rT3 TestingSt. Maries2,951Reverse T3 Test – rT3 TestingMountain Home AFB2,863Reverse T3 Test – rT3 TestingWendell2,859Reverse T3 Test – rT3 TestingHomedale2,845Reverse T3 Test – rT3 TestingAberdeen2,795Reverse T3 Test – rT3 TestingFiler2,734Reverse T3 Test – rT3 TestingIona2,640Reverse T3 Test – rT3 TestingMontpelier2,610Reverse T3 Test – rT3 TestingBellevue2,508Reverse T3 Test – rT3 TestingFort Hall2,499Reverse T3 Test – rT3 Testing