The reverse T3 blood test, which is also referred to as the reverse triiodothyronine test, is ordered by a medical professional when there is a need to evaluate thyroid gland function. It may be used in order to diagnose thyroid disease, often hyperthyroidism, and to determine the cause of the order. Those with a thyroid diagnosis may also have this test ordered regularly to monitor the effectiveness of their treatment plan.
Women who are pregnant may also have this test ordered by their provider to monitor thyroid levels. A pregnancy can cause a total increase of free and total T3 levels, even though thyroid disease may return to normal after birth.
How Is the Reverse T3 Blood Test Used?
The liver and other tissues of the body need T3 to help control how energy is used throughout the body. Most of the T3 that can be found in the body is bound to proteins that are in the blood, with only a small percentage being free, or not bound. The reverse T3 blood test can determine both levels of this hormone, especially after other thyroid-stimulating hormone [TSH] tests have come back as being abnormal.
It will typically be ordered when there are the signs and symptoms of a potential thyroid issue. This may include an increased heart rate, unexpected weight loss, higher anxiety levels, tremors in the hands, trouble sleeping, feelings of weakness, light sensitivity or disturbances, and diarrhea that seems to be without cause.
People with thyroid issues may also have issues with their eyes that may feel like an allergy attack. This includes dryness, irritation, and puffiness around the eyes. In some instances, the eyes may even begin to bulge out.
What Do the Reverse T3 Blood Test Results Mean?
There will be three total blood test results that will be considered when evaluating what may be causing a patient’s bothersome signs and symptoms. Here are what the typical test results would be and what their potential meaning would represent.
- TSH (High) / T4 (Normal) / T3 (Normal): Mild hypothyroidism.
- TSH (High) / T4 (Low) / T3 (Low/Normal): Hypothyroidism.
- TSH (Low) / T4 (Normal) / T3 (Normal): Mild hyperthyroidism.
- TSH (Low) / T4 (Normal/High) / T3 (Normal/High): Hyperthyroidism.
- TSH (Low) / T4 (Low/Normal) / T3 (Low/Normal): Secondary hypothyroidism.
- TSH (Normal) / T4 (High) / T3 (High): Thyroid hormone resistance syndrome.
The reason why the reverse T3 blood test is ordered on a regular basis once a health issue has been discovered is that the medication may cause additional symptoms by changing hormone levels. If an anti-thyroid medication stabilizes T3 levels, then the symptoms may fade and the treatment considered to be effective. If T3 levels are elevated, then new symptoms may wind up occurring.
Here’s What You Need To Know About the Reverse T3 Blood Test
Most of the time, the reverse T3 blood test will not be ordered for those patients who have been hospitalized for some reason. An acute illness will also affect hormone levels in such a way that it may seem like someone is suffering from secondary hypothyroidism. Unless there is a severe issue which needs to be addressed, this blood test will only be ordered in an outpatient situation.
There are other health issues that may also change how the body creates T3. This includes taking or being exposed to estrogen, suffering from liver disease, and have a resistance to hormones. Certain birth control pills or a large dose of aspirin can affect these blood test results. Anyone taking these items will want to discuss their impact with their medical provider if the reverse T3 blood test is being considered.
The reverse T3 test is a way to determine, therefore, how sick a person may be from a systemic or acute illness because this hormone stops the tissues from absorbing the hormone to consume energy. It is believed that high reverse T3 levels help the body be able to conserve total energy until the stress upon it has been relieved. If high levels of this hormone are in place consistently even when feeling well, then this can be symptomatic of a condition called Non-Thyrodial Illness.
The reverse T3 blood test is considered to be a controversial blood test by some medical providers. At this moment, it is not considered to be widely requested. If you are suffering from the signs and symptoms of a possible thyroid issue, however, this blood test might be one of the needed tools to help you sort out what is going on. Schedule your appointment to discuss the information in this guide and together you and your provider can determine if this blood test is right for you.