Reverse T3
A specialist thyroid blood test measuring Reverse T3, an inactive T4 metabolite that may change during illness, calorie restriction and physiological stress.
Turnaround time
2 weeks
Biomarkers count
1
Book your test
Choose Service Type
Professional phlebotomist comes to you
+ £{{ home_visit_fee }}
Visit our clinic for your test
{{ clinic_visit_fee > 0 ? '+ £' + clinic_visit_fee : '+ £0' }}
Home Visit Details
Home visits require at least 24 hours notice.
Select a clinic: Sorting by distance…
{{ clinicAddress(clinic) }}
{{ clinicAddress(selectedClinic) }}
Select a date
Select an hour
Available time slots: {{ timeSlots.length}}
Overview of the Reverse T3 Test
The Reverse T3 test is a specialist thyroid blood test measuring Reverse Triiodothyronine, commonly abbreviated to Reverse T3 or rT3.
Reverse T3 is an inactive metabolite produced when the body converts Thyroxine, or T4, through an alternative metabolic pathway.
It differs from Free T3, which represents biologically active thyroid hormone available to tissues.
Reverse T3 concentrations can change during significant illness, physiological stress, calorie restriction and other situations that alter thyroid hormone metabolism.
It is therefore a specialist marker rather than one of the principal routine tests used to assess thyroid function.
Standard thyroid assessment generally relies more heavily on TSH and Free T4, with Free T3 and thyroid antibodies added where clinically appropriate.
Reverse T3 should not be used alone to diagnose hypothyroidism or independently determine thyroid medication.
The Reverse T3 test costs £199.
Blood collection is available in clinic for an additional £35 or through an at-home phlebotomy visit for an additional £60.
What Does the Reverse T3 Test Check?
The test measures one specialist thyroid-related biomarker. This test measures 1 biomarker.
Reverse T3
Measures the inactive Reverse Triiodothyronine metabolite produced from T4 and provides specialist information about thyroid hormone metabolism.
Who May Benefit From the Reverse T3 Test?
Reverse T3 may be useful where a clinician wants additional information about thyroid hormone metabolism beyond routine TSH, Free T4 and Free T3 measurements.
People whose clinician has specifically requested Reverse T3 - This is principally a specialist thyroid investigation.
People undergoing more detailed thyroid hormone assessment - Reverse T3 can provide an additional measurement alongside standard thyroid markers.
People with unusual thyroid results during significant illness - Changes in hormone conversion can occur during systemic illness.
People with previous abnormal Reverse T3 results - Repeat testing may be considered where clinically relevant.
People undergoing specialist endocrine or metabolic assessment - Reverse T3 may occasionally form part of a broader investigation.
How to Prepare
Do not alter Levothyroxine, Liothyronine or another prescribed thyroid medicine solely to influence a Reverse T3 measurement.
Symptoms and Reasons to Consider the Reverse T3 Test
There is no symptom pattern specific to a high or low Reverse T3 result.
Persistent symptoms despite apparently reassuring routine thyroid results - A clinician may occasionally request more specialised testing.
A complex thyroid or endocrine history - Reverse T3 may provide additional information in selected cases.
Significant recent illness or physiological stress - Thyroid hormone conversion patterns can change during illness.
Substantial calorie restriction or rapid weight change - Energy availability can influence thyroid hormone metabolism.
A previous Reverse T3 result requires follow-up - Repeat testing can provide trend information where clinically useful.
A clinician has specifically requested the test - This remains the most appropriate indication.
Fatigue, weight change, cold intolerance, hair changes and poor concentration are not specific to Reverse T3.
These symptoms can have many causes and should usually be assessed with appropriate routine thyroid, nutritional, metabolic and general health testing first.
How to Book Your Reverse T3 Test
Reverse T3 can be booked as a specialist private thyroid blood test with either clinic-based or at-home phlebotomy.
Choose the Reverse T3 Test
Select the £199 specialist thyroid marker.
Select your collection option
Choose in-clinic phlebotomy for +£35 or an at-home phlebotomy visit for +£60.
Attend your appointment
A trained healthcare professional collects the required blood specimen either at the clinic or at your home.
Laboratory analysis
Reverse T3 is measured using the specialist thyroid laboratory pathway.
Receive your results securely
Your authorised Reverse T3 result is delivered securely.
When Will I Receive My Results?
Reverse T3 is a specialist assay and results are generally expected within approximately 15 working days.
Specialist testing can occasionally take longer than routine thyroid markers.
Understanding Your Results
Reverse T3 should not normally be interpreted in isolation.
A higher or lower result needs to be considered alongside the reason for testing, current health status, medication and other thyroid markers.
Reverse T3 may change during systemic illness or altered energy availability without indicating primary thyroid-gland disease.
TSH and Free T4 remain central measurements when routine thyroid dysfunction is being assessed.
Where appropriate, Free T3, thyroid antibodies and other endocrine investigations can provide additional context.
Treatment decisions should not be based solely on a Reverse T3 result.
Why Book With London Blood Tests?
London Blood Tests provides access to specialist Reverse T3 testing with flexible professional blood collection.
Specialist thyroid marker - Reverse T3 provides information distinct from routine TSH, Free T4 and Free T3.
Single focused investigation - The test can be added where a clinician specifically requires rT3.
Useful alongside a broader thyroid profile - Results can be considered with standard thyroid hormone measurements.
Professional blood collection - Samples are taken by trained healthcare professionals.
Flexible phlebotomy options - Choose in-clinic collection for +£35 or an at-home phlebotomist for +£60.
Specialist turnaround - Results are generally expected within approximately 15 working days.
Clear pricing - Reverse T3 costs £199, with collection charged separately.
Private Reverse T3 Blood Test in London
London Blood Tests provides private Reverse T3 testing in London for £199.
Professional blood collection can be arranged in clinic for +£35 or through an at-home phlebotomy visit for +£60.
The test measures Reverse Triiodothyronine, an inactive metabolite of T4, and is intended as a specialist thyroid-related investigation.
Results are generally expected within approximately 15 working days.