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Midwest · Reverse T3 Test – rT3 Testing

Reverse T3 Test – rT3 Testing in Iowa

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 Iowa

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

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

Des Moines514,654Reverse T3 Test – rT3 TestingDavenport280,282Reverse T3 Test – rT3 TestingCedar Rapids192,714Reverse T3 Test – rT3 TestingIowa City120,015Reverse T3 Test – rT3 TestingWaterloo114,594Reverse T3 Test – rT3 TestingSioux City111,924Reverse T3 Test – rT3 TestingDubuque67,916Reverse T3 Test – rT3 TestingWest Des Moines67,640Reverse T3 Test – rT3 TestingAnkeny66,346Reverse T3 Test – rT3 TestingAmes66,027Reverse T3 Test – rT3 TestingCouncil Bluffs62,617Reverse T3 Test – rT3 TestingUrbandale45,037Reverse T3 Test – rT3 TestingMarion41,023Reverse T3 Test – rT3 TestingCedar Falls40,500Reverse T3 Test – rT3 TestingBettendorf38,631Reverse T3 Test – rT3 TestingMarshalltown27,570Reverse T3 Test – rT3 TestingMason City27,385Reverse T3 Test – rT3 TestingOttumwa25,379Reverse T3 Test – rT3 TestingFort Dodge24,826Reverse T3 Test – rT3 TestingClinton24,651Reverse T3 Test – rT3 TestingBurlington24,160Reverse T3 Test – rT3 TestingMuscatine23,759Reverse T3 Test – rT3 TestingWaukee23,441Reverse T3 Test – rT3 TestingJohnston23,418Reverse T3 Test – rT3 TestingCoralville22,226Reverse T3 Test – rT3 TestingNorth Liberty19,976Reverse T3 Test – rT3 TestingAltoona19,345Reverse T3 Test – rT3 TestingClive18,323Reverse T3 Test – rT3 TestingNewton15,688Reverse T3 Test – rT3 TestingIndianola15,544Reverse T3 Test – rT3 TestingGrimes14,842Reverse T3 Test – rT3 TestingNorwalk12,592Reverse T3 Test – rT3 TestingBoone12,509Reverse T3 Test – rT3 TestingOskaloosa11,552Reverse T3 Test – rT3 TestingSpencer11,292Reverse T3 Test – rT3 TestingStorm Lake11,166Reverse T3 Test – rT3 TestingLe Mars10,462Reverse T3 Test – rT3 TestingPella10,414Reverse T3 Test – rT3 TestingFort Madison10,340Reverse T3 Test – rT3 TestingWaverly10,278Reverse T3 Test – rT3 TestingCarroll10,261Reverse T3 Test – rT3 TestingPleasant Hill10,203Reverse T3 Test – rT3 TestingKeokuk9,977Reverse T3 Test – rT3 TestingFairfield9,653Reverse T3 Test – rT3 TestingGrinnell9,481Reverse T3 Test – rT3 TestingMount Pleasant8,996Reverse T3 Test – rT3 TestingDenison8,323Reverse T3 Test – rT3 TestingSioux Center8,090Reverse T3 Test – rT3 TestingPerry7,836Reverse T3 Test – rT3 TestingWebster City7,825Reverse T3 Test – rT3 TestingDecorah7,767Reverse T3 Test – rT3 TestingClear Lake7,673Reverse T3 Test – rT3 TestingCreston7,594Reverse T3 Test – rT3 TestingKnoxville7,537Reverse T3 Test – rT3 TestingCharles City7,399Reverse T3 Test – rT3 TestingWashington7,314Reverse T3 Test – rT3 TestingHiawatha7,184Reverse T3 Test – rT3 TestingBondurant7,163Reverse T3 Test – rT3 TestingNevada7,017Reverse T3 Test – rT3 TestingAtlantic6,795Reverse T3 Test – rT3 Testing