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Mountain West · Reverse T3 Test – rT3 Testing

Reverse T3 Test – rT3 Testing in Montana

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 Montana

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

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

Billings124,973Reverse T3 Test – rT3 TestingMissoula92,863Reverse T3 Test – rT3 TestingGreat Falls62,112Reverse T3 Test – rT3 TestingBozeman51,574Reverse T3 Test – rT3 TestingButte34,368Reverse T3 Test – rT3 TestingHelena32,060Reverse T3 Test – rT3 TestingKalispell24,260Reverse T3 Test – rT3 TestingBelgrade10,555Reverse T3 Test – rT3 TestingHavre9,417Reverse T3 Test – rT3 TestingAnaconda9,380Reverse T3 Test – rT3 TestingHelena Valley Southeast9,316Reverse T3 Test – rT3 TestingHelena Valley West Central8,550Reverse T3 Test – rT3 TestingMiles City8,441Reverse T3 Test – rT3 TestingLivingston8,110Reverse T3 Test – rT3 TestingEvergreen7,988Reverse T3 Test – rT3 TestingWhitefish7,783Reverse T3 Test – rT3 TestingLaurel7,164Reverse T3 Test – rT3 TestingLockwood7,162Reverse T3 Test – rT3 TestingSidney6,240Reverse T3 Test – rT3 TestingLewistown5,967Reverse T3 Test – rT3 TestingFour Corners5,649Reverse T3 Test – rT3 TestingColumbia Falls5,304Reverse T3 Test – rT3 TestingOrchard Homes5,170Reverse T3 Test – rT3 TestingPolson5,161Reverse T3 Test – rT3 TestingGlendive4,928Reverse T3 Test – rT3 TestingBigfork4,683Reverse T3 Test – rT3 TestingHelena Valley Northwest4,653Reverse T3 Test – rT3 TestingHamilton4,632Reverse T3 Test – rT3 TestingLolo4,338Reverse T3 Test – rT3 TestingMalmstrom AFB4,098Reverse T3 Test – rT3 TestingDillon3,930Reverse T3 Test – rT3 TestingHardin3,754Reverse T3 Test – rT3 TestingHelena Valley Northeast3,607Reverse T3 Test – rT3 TestingNorth Browning3,253Reverse T3 Test – rT3 TestingGlasgow3,192Reverse T3 Test – rT3 TestingBig Sky3,141Reverse T3 Test – rT3 TestingShelby3,139Reverse T3 Test – rT3 TestingCut Bank3,049Reverse T3 Test – rT3 TestingDeer Lodge2,938Reverse T3 Test – rT3 TestingConrad2,758Reverse T3 Test – rT3 TestingLibby2,745Reverse T3 Test – rT3 TestingMontana City2,735Reverse T3 Test – rT3 TestingWolf Point2,638Reverse T3 Test – rT3 TestingLakeside2,463Reverse T3 Test – rT3 TestingLame Deer2,231Reverse T3 Test – rT3 TestingTownsend2,224Reverse T3 Test – rT3 TestingEast Missoula2,162Reverse T3 Test – rT3 TestingColstrip2,094Reverse T3 Test – rT3 TestingThree Forks2,084Reverse T3 Test – rT3 TestingColumbus2,069Reverse T3 Test – rT3 TestingPablo2,037Reverse T3 Test – rT3 TestingRed Lodge2,032Reverse T3 Test – rT3 TestingMalta2,031Reverse T3 Test – rT3 TestingCrow Agency1,993Reverse T3 Test – rT3 TestingStevensville1,959Reverse T3 Test – rT3 TestingKing Arthur Park1,951Reverse T3 Test – rT3 TestingClancy1,902Reverse T3 Test – rT3 TestingManhattan1,884Reverse T3 Test – rT3 TestingWest Glendive1,868Reverse T3 Test – rT3 TestingChoteau1,826Reverse T3 Test – rT3 Testing