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Pacific · Reverse T3 Test – rT3 Testing

Reverse T3 Test – rT3 Testing in Washington

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 Washington

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

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

Seattle3,438,221Reverse T3 Test – rT3 TestingSpokane440,270Reverse T3 Test – rT3 TestingKennewick241,230Reverse T3 Test – rT3 TestingBremerton219,538Reverse T3 Test – rT3 TestingTacoma217,332Reverse T3 Test – rT3 TestingOlympia200,836Reverse T3 Test – rT3 TestingVancouver188,331Reverse T3 Test – rT3 TestingMarysville164,655Reverse T3 Test – rT3 TestingBellevue149,365Reverse T3 Test – rT3 TestingKent134,890Reverse T3 Test – rT3 TestingYakima130,440Reverse T3 Test – rT3 TestingBellingham129,601Reverse T3 Test – rT3 TestingEverett110,438Reverse T3 Test – rT3 TestingRenton105,313Reverse T3 Test – rT3 TestingSpokane Valley102,178Reverse T3 Test – rT3 TestingFederal Way99,792Reverse T3 Test – rT3 TestingKirkland91,656Reverse T3 Test – rT3 TestingAuburn85,306Reverse T3 Test – rT3 TestingPasco76,398Reverse T3 Test – rT3 TestingRedmond72,166Reverse T3 Test – rT3 TestingWenatchee71,119Reverse T3 Test – rT3 TestingLongview67,958Reverse T3 Test – rT3 TestingMount Vernon67,767Reverse T3 Test – rT3 TestingSouth Hill66,713Reverse T3 Test – rT3 TestingSammamish66,532Reverse T3 Test – rT3 TestingLakewood62,972Reverse T3 Test – rT3 TestingRichland59,718Reverse T3 Test – rT3 TestingShoreline58,213Reverse T3 Test – rT3 TestingLacey52,572Reverse T3 Test – rT3 TestingBurien51,646Reverse T3 Test – rT3 TestingBothell47,355Reverse T3 Test – rT3 TestingEdmonds42,622Reverse T3 Test – rT3 TestingPuyallup42,366Reverse T3 Test – rT3 TestingIssaquah39,057Reverse T3 Test – rT3 TestingLynnwood38,812Reverse T3 Test – rT3 TestingParkland38,092Reverse T3 Test – rT3 TestingLake Stevens35,135Reverse T3 Test – rT3 TestingSpanaway34,670Reverse T3 Test – rT3 TestingUniversity Place34,565Reverse T3 Test – rT3 TestingWalla Walla33,765Reverse T3 Test – rT3 TestingGraham33,727Reverse T3 Test – rT3 TestingPullman32,968Reverse T3 Test – rT3 TestingDes Moines32,631Reverse T3 Test – rT3 TestingSeaTac30,867Reverse T3 Test – rT3 TestingOrchards28,371Reverse T3 Test – rT3 TestingMaple Valley27,643Reverse T3 Test – rT3 TestingCamas25,774Reverse T3 Test – rT3 TestingMill Creek East25,528Reverse T3 Test – rT3 TestingMercer Island25,506Reverse T3 Test – rT3 TestingTumwater24,855Reverse T3 Test – rT3 TestingMoses Lake24,764Reverse T3 Test – rT3 TestingNorth Lynnwood24,562Reverse T3 Test – rT3 TestingBainbridge Island24,557Reverse T3 Test – rT3 TestingOak Harbor24,267Reverse T3 Test – rT3 TestingKenmore23,556Reverse T3 Test – rT3 TestingEastmont23,088Reverse T3 Test – rT3 TestingUnion Hill-Novelty Hill23,060Reverse T3 Test – rT3 TestingCottage Lake22,779Reverse T3 Test – rT3 TestingMartha Lake22,251Reverse T3 Test – rT3 TestingBonney Lake22,229Reverse T3 Test – rT3 Testing