Reverse T3 blood test in Chiswick
A blood test for reverse T3, an inactive form of thyroid hormone, for people exploring tiredness, weight change or feeling cold with a practitioner after a standard thyroid profile, or monitoring thyroid treatment.
What the test measures
The thyroid gland mainly releases thyroxine (T4), which the body converts into active tri-iodothyronine (T3). Some T4 is instead converted into reverse T3 (rT3), a form that does not switch on the same cell activity. The body naturally produces more reverse T3 during illness, calorie restriction, intense stress and with some medicines, as a way of conserving energy.
Reverse T3 is not part of standard NHS thyroid testing, which relies on TSH and free T4, sometimes with free T3. Most UK endocrinologists do not use reverse T3 to diagnose thyroid conditions or to guide treatment, so it should be seen as additional detail read alongside a full thyroid profile.
The price includes the sample taken at our Chiswick clinic, analysis at the Randox accredited laboratory, a practitioner review of your result, and a GP feedback report on request.
Who it is for
- You have tiredness, weight change or feel cold and have already had a standard thyroid profile.
- You are recovering from illness, have been dieting heavily or are under prolonged stress and want to understand your thyroid hormones.
- You take thyroid medicine and would like a practitioner to look at your thyroid hormones in more detail.
- Your practitioner has suggested reverse T3 as part of a wider review.
Understanding your result
Your report shows your reverse T3 level with the laboratory reference range. A higher level can be seen during or after illness, with calorie restriction or with certain medicines such as amiodarone, beta blockers and steroids, and it often settles once the cause passes. A lower level is rarely significant on its own.
Reverse T3 is only meaningful alongside TSH, free T4 and free T3. A result outside the range is a prompt for discussion with your practitioner, not a diagnosis, and any changes to thyroid medicine should be made with your GP or endocrinologist.
Preparing for your test
This test does not require fasting. If you take levothyroxine or other thyroid medicine, have the test before your daily dose, and try to keep the time of day consistent if you test again. Stop biotin supplements for at least 48 hours beforehand, as biotin can interfere with thyroid immunoassays. Let us know about any recent illness and any medicines you take.
Reverse T3 is best read with a full picture of thyroid function, which you can find on our thyroid blood tests page. If tiredness is your main concern, Tired All The Time looks at several common causes. See every blood test and price in Chiswick.
Questions
How much is a reverse T3 test in Chiswick?
The Reverse T3 test costs £299. It includes the blood sample at our Chiswick clinic, analysis at the Randox accredited laboratory, a practitioner review of your result, and a GP feedback report on request.
Do I need a reverse T3 test if my TSH is normal?
Most people do not. TSH and free T4 are the main tests for thyroid function. Reverse T3 can add detail but does not usually change the diagnosis.
What can raise reverse T3?
Illness, very low-calorie diets, intense stress and some medicines can increase reverse T3, often temporarily.
Can reverse T3 be used to adjust my thyroid medicine?
Thyroid medicine is normally adjusted using TSH and free T4. Please discuss any change with your GP or endocrinologist.
