Thyroid Function Test – TFT Test

A thyroid function blood test checks the levels of thyroid hormone, as well as TSH and sometimes other thyroid related hormones or antibodies in the blood stream. The hormone levels give an idea as to how the thyroid is functioning.

Results can indicate if someone requires prescription medication, further tests or specialist referral.


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What is the thyroid gland?

The thyroid is a small butterfly shaped gland that lies in the front of your neck just under your voice box. It produces hormones which are released into the blood stream. These hormones help regulate the body’s metabolism (how fast or slow the organs work) and in turn help to keep bodily functions working normally, for example, breathing, digestion, heart rate, menstrual cycle, body weight and temperature and cholesterol levels.

How does it work?

The thyroid is a gland in the endocrine system that produces and secretes hormones into the blood to be carried to the body’s cells. It produces hormones called T3 (tri iodothyronine) and T4 (thyroxine) and these regulate the speed at which your cells work. These are made using iodine which is present in foods such as dairy products, seafood and salt.

Production of these hormones is triggered by release of Thyroid Stimulating Hormone (TSH) from the pituitary gland in the brain, whose job is to check the thyroid hormone blood levels.

The thyroid can over or under produce thyroid hormone, which are known as either an overactive or underactive thyroid. These conditions have quite different physical manifestations.

If thyroid hormone levels in the blood are abnormal, specific prescription medication may be required to treat this imbalance. Treatment can be very effective in balancing your thyroid hormones leading to a significant improvement in well- being in many individuals.


Thyroid Blood Test options we offer

  • We offer 3 different Thyroid Profile blood tests, depending on which parameters you would like to measure to gauge Thyroid Health.

  • These may include Thyroxine (T4) and Triiodothyronine (T3) produced by the Thyroid Gland, Thyroid Stimulating Hormone (TSH) released by the Pituitary Gland.

  • These tests are recommended by doctors for patients who are at-risk, or showing symptoms of underactive or overactive thyroid disease:
    • Underactive thyroid is known as hypothyroidism, such as Hashimoto’s disease.
    • Overactive thyroid is known as hyperthyroidism, such as Graves’ disease.
  • Some tests also measure levels of Thyroid Antibodies. These thyroid tests are used when autoimmune thyroid diseases, such as Graves disease or Hashimoto Thyroiditis, are suspected. 


If you are looking for a broader health assessment that includes Thyroid Function, Thyroid Health is also assessed in all of our General Wellness Screens. These consultations also require just 15 minutes, are available at all our London clinic locations, all of that time will be spent with one of our private doctors. Each Thyroid Health Test will require an addition fee for the consultation time with a GP. 


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Thyroid Test – Profile 1 (TF)

£90 – 4-6 Hours

  • Thyroid Function Test Includes:
    • Free T4 
    • TSH

Thyroid Test – Profile 2 (TF2)

£224 – 2 Days

  • Thyroid Blood Test Includes:
    • T4
    • Free T3
    • Free T4
    • TSH
    • Thyroid Antibodies

Thyroid Test – Profile 3 (TF3)

£124.80 – 4-6 Hours

  • Thyroid Test Includes:
    • Free T3
    • Free T4
    • TSH

These are just the overactive and underactive Thyroid test options; please go here for a full list of all of the private blood tests we offer.


Private Blood Test for Thyroid Function Test Locations: Bank, Canary Wharf, Chislehurst, Chiswick, Esher, Fulham, Guildford, Hampstead, Islington, Kensington, Kings Cross, Liverpool Street, London Bridge, Oxford Street, St Albans, Twickenham, Victoria and Wandsworth or you can book an Online Doctor

Written by Dr Julianne Barry, General Practitioner at London Doctors Clinic

Updated: April 2022

Review date: April 2025