Pacific · Reverse T3 Test – rT3 Testing

Reverse T3 Test – rT3 Testing in California

This page explains the reverse t3 test – rt3 testing, what it measures, and how to order it. The Reverse T3 Test measures the level of reverse triiodothyronine in the blood to assess thyroid function under certain conditions.

Sample typeBlood draw at a collection lab

ReferralNo referral required

What this test is

The Reverse T3 Test is a blood test that evaluates the level of reverse triiodothyronine (rT3), a hormone related to thyroid function. It is often used to assess thyroid activity in the context of nonthyroidal illness syndrome.

What it measures

Reverse T3 — reflects the body's conversion of thyroxine (T4) to triiodothyronine (T3)

What the test involves

The test involves a standard blood draw, typically from a vein in the arm. The collected sample is then analyzed in a laboratory.

Why it is often ordered

Clinicians may order this test to investigate thyroid function when a patient has symptoms that suggest abnormal thyroid activity. It helps differentiate between thyroid disorders and other conditions affecting thyroid hormone levels.

Preparation

Preparation for the Reverse T3 Test may vary, so it is important to follow the specific instructions provided by the laboratory conducting the test.

How results are reported

Results of the Reverse T3 Test are reported as a concentration of rT3 in the blood. Reference ranges can vary between laboratories, so results should be interpreted in context.

Before you go

Sample collection method
Preparation instructions
Turnaround time

Cities

Reverse T3 Test – rT3 Testing in California communities

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

Los Angeles12,121,244Reverse T3 Test – rT3 Testing San Francisco3,290,197Reverse T3 Test – rT3 Testing San Diego3,084,174Reverse T3 Test – rT3 Testing Riverside2,022,285Reverse T3 Test – rT3 Testing Sacramento1,924,167Reverse T3 Test – rT3 Testing San Jose1,729,879Reverse T3 Test – rT3 Testing Fresno719,558Reverse T3 Test – rT3 Testing Concord640,270Reverse T3 Test – rT3 Testing Bakersfield590,845Reverse T3 Test – rT3 Testing Mission Viejo588,540Reverse T3 Test – rT3 Testing Murrieta509,526Reverse T3 Test – rT3 Testing Long Beach466,565Reverse T3 Test – rT3 Testing Oakland437,548Reverse T3 Test – rT3 Testing Stockton406,822Reverse T3 Test – rT3 Testing Victorville389,060Reverse T3 Test – rT3 Testing Modesto382,994Reverse T3 Test – rT3 Testing Lancaster381,732Reverse T3 Test – rT3 Testing Oxnard366,330Reverse T3 Test – rT3 Testing Indio361,831Reverse T3 Test – rT3 Testing Anaheim348,204Reverse T3 Test – rT3 Testing Antioch322,796Reverse T3 Test – rT3 Testing Santa Rosa314,196Reverse T3 Test – rT3 Testing Santa Ana313,818Reverse T3 Test – rT3 Testing Irvine297,868Reverse T3 Test – rT3 Testing Santa Clarita275,230Reverse T3 Test – rT3 Testing Chula Vista274,818Reverse T3 Test – rT3 Testing Visalia249,804Reverse T3 Test – rT3 Testing Fremont231,502Reverse T3 Test – rT3 Testing San Bernardino220,821Reverse T3 Test – rT3 Testing Thousand Oaks211,045Reverse T3 Test – rT3 Testing Moreno Valley208,371Reverse T3 Test – rT3 Testing Fontana208,087Reverse T3 Test – rT3 Testing Salinas199,290Reverse T3 Test – rT3 Testing Huntington Beach198,735Reverse T3 Test – rT3 Testing Santa Barbara198,240Reverse T3 Test – rT3 Testing Glendale196,512Reverse T3 Test – rT3 Testing Hemet191,170Reverse T3 Test – rT3 Testing Vallejo181,882Reverse T3 Test – rT3 Testing Elk Grove175,510Reverse T3 Test – rT3 Testing Ontario175,223Reverse T3 Test – rT3 Testing Oceanside174,461Reverse T3 Test – rT3 Testing Rancho Cucamonga173,946Reverse T3 Test – rT3 Testing Garden Grove172,708Reverse T3 Test – rT3 Testing Palmdale167,987Reverse T3 Test – rT3 Testing Santa Cruz165,933Reverse T3 Test – rT3 Testing Hayward162,254Reverse T3 Test – rT3 Testing Corona157,844Reverse T3 Test – rT3 Testing Merced157,617Reverse T3 Test – rT3 Testing Sunnyvale155,550Reverse T3 Test – rT3 Testing Pomona151,592Reverse T3 Test – rT3 Testing Escondido151,443Reverse T3 Test – rT3 Testing Torrance147,156Reverse T3 Test – rT3 Testing Roseville145,687Reverse T3 Test – rT3 Testing Fairfield145,163Reverse T3 Test – rT3 Testing Fullerton142,964Reverse T3 Test – rT3 Testing Santa Maria142,230Reverse T3 Test – rT3 Testing Orange139,195Reverse T3 Test – rT3 Testing Pasadena138,771Reverse T3 Test – rT3 Testing Yuba City129,536Reverse T3 Test – rT3 Testing Santa Clara127,922Reverse T3 Test – rT3 Testing