Thyroid Function Blood Test

ULTIMATE VITAMINS BLOOD TEST OVERVIEW

Our vitamin blood test panel includes Total Vitamin B12, Active Vitamin B12 (holotranscobalamin), Vitamin D, and Vitamin B9 (folate) and offers a comprehensive overview of key nutrients essential for energy production, neurological function, immune health, and red blood cell formation.

Check and manage the level of vitamins B12 (both active and total), vitamin B9 (folate) and Vitamin D, in your body, with this test.

Vitamin B12

Vitamin B12 is essential for most body systems, particularly in haematology with the manufacture of blood cells and hence healthy function of the organism as a whole, including the nervous system. Symptoms of low vitamin B12 are abundant, including tiredness, lack of energy, headaches and many others.

This test measures both active and total levels of Vitamin B12

Total B12 refers to the measurement of all forms of vitamin B12 present in the blood. This includes both active B12 (methylcobalamin and adenosylcobalamin) and inactive B12 forms (such as cyanocobalamin). The measurement of total B12 provides an overall picture of the total B12 content in the bloodstream, regardless of whether the B12 forms are actively available for body use.

Active B12, also known as cobalamin, refers to the biologically active forms of vitamin B12 that are immediately available for the body to use. The two primary active forms are methylcobalamin and adenosylcobalamin. These active forms play essential roles in various physiological processes, particularly in energy metabolism and nerve function.

Why it is important to measure both.

The distinction between total B12 and active B12 is crucial because not all forms of B12 are biologically active or readily usable by the body. Cyanocobalamin, for example, is an inactive form of B12 that requires conversion into active forms before the body can utilise it. Methylcobalamin and adenosylcobalamin are already in their active forms and can be directly utilized by cells.

In some cases, only total B12 levels are measured, which may not give a complete assessment of B12 status. It is often beneficial to measure active B12 levels (or other markers like free B12/holotranscobalamin) to better understand the body`s immediate access to functional B12.

This test measures both forms.

Vitamin D

Vitamin D is a fat-soluble vitamin that plays a crucial role in various physiological processes in the human body. Vitamin D is produced in the skin when it is exposed to sunlight and manifests itself in the more biologically active form of D3.

Vitamin D is important for the following:

Bone Health: Vitamin D is essential for the absorption of calcium and phosphate from the gastrointestinal tract. These minerals are critical for maintaining strong and healthy bones. Without enough vitamin D, the body cannot absorb enough calcium, leading to weakened bones and conditions like rickets in children and osteoporosis in adults.

Immune System Support: Vitamin D plays a role in supporting the immune system. It helps the body fight off infections and illnesses, and deficiencies in vitamin D have been associated with an increased risk of infections.

Cell Growth and Function: Vitamin D is involved in regulating cell growth and differentiation. It may have a role in preventing the development of certain cancers, though more research is needed in this area.

Mood and Mental Health: Some studies suggest that vitamin D may have a role in mood regulation, and deficiencies have been linked to conditions like depression and seasonal affective disorder (SAD).

Heart Health: Adequate vitamin D levels are associated with a lower risk of heart disease. It may help regulate blood pressure and reduce inflammation.

Muscle Function: Vitamin D is important for muscle strength and function, and deficiency can lead to muscle weakness and pain.

Autoimmune Diseases: Some autoimmune diseases, such as multiple sclerosis, rheumatoid arthritis, and type 1 diabetes, have been linked to low vitamin D levels.

Regulation of Calcium: Vitamin D helps maintain proper levels of calcium in the blood, which is crucial for muscle function, nerve transmission, and blood clotting.

Longevity: Some research suggests that maintaining adequate vitamin D levels may be associated with a longer lifespan and reduced risk of chronic diseases.

Vitamin D can be obtained through dietary sources such as fatty fish (e.g., salmon and mackerel), fortified foods (e.g., fortified milk and cereals), and supplements. However, the body can also produce vitamin D when the skin is exposed to sunlight. Therefore, a balance between sun exposure, diet, and supplements can help ensure sufficient vitamin D levels in the body.

It is important to note that excessive vitamin D intake can lead to toxicity, so it is advisable to consult with a healthcare professional before taking high-dose supplements. Additionally, individual vitamin D requirements can vary, so it is essential to monitor your levels through blood tests if you have concerns about deficiency or excess.

Vitamin B9 - Folate

Vitamin B9, also known as folate or folic acid, is a water-soluble B vitamin that plays a crucial role in various essential functions within the body. It is an essential nutrient, meaning that it must be obtained from the diet because the human body cannot produce it on its own.

If you’re not sure exactly what you need, we advise all our clients to consult with a GP or one of our Registered Nutritionists before taking any blood tests. However, below you can find more information about this panel, and we hope it will help.

IS THE ULTIMATE VITAMINS BLOOD TEST RIGHT FOR ME?

This vitamin panel may be right for you if you're experiencing symptoms such as fatigue, brain fog, low mood, frequent illness, tingling sensations, or unexplained weakness.

All of which can be linked to deficiencies in B12, folate, or vitamin D.

You should also have this test if you follow a restricted diet (such as vegan or vegetarian), have gastrointestinal conditions that affect absorption (like coeliac or Crohn’s disease), are pregnant or planning pregnancy, or spend limited time in sunlight.

This test helps identify subtle or early-stage deficiencies that may not show up on a general blood test.

WHY HAVE THE ULTIMATE VITAMINS BLOOD TEST?

Testing for vitamin B12, active B12, folate (B9), and vitamin D is important because these nutrients play vital roles in maintaining energy levels, brain function, red blood cell production, immune defence, and bone health.

Deficiencies can develop gradually and often go unnoticed until they cause more serious symptoms or complications, such as anaemia, nerve damage, cognitive changes, or bone loss.

SYMPTOMS AND TAGS

Chronic fatigue, Fatigue, Headache and Tiredness

1. Fill out the contact form on the main page
2. Choose your preferred panel
3. Select between a Home Kit (via post), a Clinic Appointment, or VIP service
4. Make the payment online.
5. We'll contact you to arrange a clinic appointment or a VIP service and email you with your home kit delivery details.

Not sure which panel or test is right for you? Reach out to one of our Registered Nutritionists  

COLLECTION OPTIONS

1. VIP: Home/Office/Hotel visit by our phlebotomist – Available in London UK only (1-3 days)
2. Clinic visit (24+ UK locations, 1-3 days)
3. At-home kit (3-6 days)

VIP Phlebotomist Visit (London Only):

Perfect for busy individuals or corporate teams.

• Available across London.
• Once payment is received, our team will contact you to arrange your appointment — usually the same day if booked before 10 am, or the next day if later.
• Additional patients beyond 10 are charged £25 each, invoiced after the visit.
• Please select the total number of blood tests at checkout so our phlebotomist can bring the right equipment.
• Your blood will be collected by a trained phlebotomist and delivered directly to our lab for fast, accurate results.

In-Clinic Appointment:

Quick, professional, and convenient.

• Same or next working day appointment.
• We’ll contact you within 60 minutes of booking to arrange your visit.
• Your blood will be collected by a trained phlebotomist and sent directly to our lab for fast, accurate results.
• Choose your nearest clinic and skip the wait. (Check Locations)

Home Kit:

Test from the comfort of your home — anywhere in mainland UK.

• Everything you need to collect your sample in about 15 minutes.
• Return it to our lab via Prepaid Royal Mail  Tracked 24.
• Free replacement kit if anything goes wrong or more blood is needed — so you can order with confidence.

This test should be taken after any symptoms of short term illness have resolved.

If you are taking biotin supplements, stop taking them 72 hours before the test.

Clinic appointment - how to prepare for the Thyroid Function Blood Test

If you are coming into one of our clinics for the test, this is what you need to do before you arrive:

• Read the instructions in the SPECIAL INSTRUCTIONS section
• Drink plenty of water about an hour before the appointment.
• Avoid coffee/tea/energy drinks. Water is good!
• That’s it! We’ll do the rest.

Home test kit - how it works with the Thyroid Function Blood Test

Our blood test kits are simple and convenient.

The most important step in doing a blood test at home is to read the instructions very carefully. The process is very simple, but there are a few pitfalls you need to be aware of - you will save yourself a lot of time if you do it right the first time around!

Full printed instructions will arrive with your kit - please read them carefully.

Drink plenty before taking the sample and warm your hands up in the sink with warm water for a few minutes. This will make your blood flow much better.

• Fill the tubes to the top line. We don’t need much blood; filling tubes to the top line is about 15 drops of blood.
• Post the samples on the same day you take them, before midday, Monday to Thursday. If you post it any other time it might get to us late or be stuck at a sorting office over the weekend. You will then have to do it again.
• Package the sample in the same box the kit came in. Otherwise, Royal Mail or DPD will reject it. The sample tubes go into a pouch, then into a cardboard box, and then into a return envelope. All of this is provided in the kit: please use it.

We look forward to receiving your sample in our lab!

HORMONES

• Unbound thyroxine (Free T4)
• Unbound triiodothyronine (Free T3)
• Thyroid Stimulating Hormone (TSH)

We always encourage you to visit one of our Clinique for any of our blood tests.

HOME KIT VIA ROYAL MAIL TRACKED 24

This service costs additional £19.00 and includes:

Available everywhere in mainland UK.

Includes everything you need to take a safe and suitable blood sample in about 15 minutes.

Post the sample back to our laboratory via Royal Mail Tracked 24.

CLINIC APPOINTMENT - SAME OR NEXT WORKING DAY

This service costs additional £38.00 and includes:

• No waiting. We will call you within 2 hours to book your appointment for the same day when purchased before 10am or following day if later than 10am.
• Quick blood collection from your vein, by our professional phlebotomist.
• Blood transported directly to our laboratory - for quick and accurate results.

No home kit exclusion for this panel. We always recommend an in Clinique appointment when the time permits.

We are extremely fast, with some results available within hours and others within a working day or less, from the time your sample is in our lab. However, this is not a guarantee and should not be taken as such. This is the guideline turnaround time that can be shorter or longer.

THIS IS NOT A GUARANTEED TURNAROUND TIME.

We are extremely proud of our very short turnaround times and very efficient laboratory processes; you will receive your results as soon as they are available and have completed clinical validation.

Whilst we accommodate the shortest time scales, with some results available within hours, for some tests the turnaround time is 1-3 working days.

DR. ADAM STATEN - GP VIEW AND RED FLAG SYMPTOMS

Usually, the thyroid gland in the neck and the pituitary gland in the brain work in harmony to effectively regulate your metabolism and keep you feeling well.

The brain produces Thyroid Stimulating Hormone (TSH) to prompt the thyroid to produce two hormones, thyroxine (T4) and triiodothyronine (T3).

As the levels of these two hormones rise, production of TSH in the brain is down regulated. As the levels of T3 and T4 fall, the brain produces more TSH to stimulate the thyroid gland to work harder.

Testing these three hormones together tells us how well your thyroid is functioning, helps to check pituitary function, and may even help us detect a problem with your thyroid before you have symptoms.

T3 and T4 exist in the blood in ‘free’ form or bound to proteins. The free forms are the active forms and these are what we measure to give an accurate impression of your thyroid function. Most tests for thyroid function just check TSH and T4, but a minority of people are unable to convert T4 to the more active T3 and so we check all 3 hormones to ensure that all elements of your thyroid function are working properly.

When the thyroid is underactive, everything essentially slows down. This results in weight gain, feeling cold all the time, dry skin and hair loss, and feeling tired and low. If the thyroid is overactive, everything speeds up. This causes weight loss, a racing pulse, tremor, feeling jittery and anxious, and the feeling of being too hot all the time.

Red flag symptoms for the Thyroid Function Blood Test

Even if your blood tests are normal, you should see a doctor if you have any of the symptoms below because they may be a sign of serious underlying illness.

Unexplained weight loss.

Drenching sweats during the night.

Persistent fevers.

Progressively severe symptoms of any kind.

How do you test thyroid Function?

To test thyroid function we test for the two hormones that are produced by the thyroid (thyroxine and triiodothyronine). These are the active hormones that control your metabolism. Low levels suggest the thyroid is underactive, high levels suggest it is overactive. We also test the hormone secreted from the brain called Thyroid Stimulating Hormone (TSH). This helps us to establish whether thyroid problems are due to a problem with the thyroid or, more rarely, with the brain.

Why do you need to check for three different hormones?

Looking at the levels of T4, T3 and TSH together gives us a lot of information about the underlying cause of any thyroid disorder and helps us to establish where exactly the problem lies. Checking these three together can also help us identify early disease that may not yet be clinically apparent.

Should I test for antibodies as well?

Most thyroid problems are caused by autoimmune diseases – most commonly Grave’s disease and Hashimoto’s thyroiditis. The presence of autoantibodies helps us to establish that this is the case. Some people will have these antibodies but will not have a problem with thyroid function. These people may never develop thyroid disease, but they are at higher risk of doing so and may choose to have regular monitoring so that any problem is picked up early.

If you would like to test for antibodies then please have a look at our Ultimate Thyroid Function Blood Test.

Can I see a GP to discuss my Results?

Yes, usually the same or next day.

Our fantastic partner clinical team of consultants and GPs. Once you have your results, you can book an online video consultation to discuss your results.

Our clinical team consists of practicing NHS and private GPs, who work closely with our laboratory and can tell you what your blood test results mean for you. Having an integrated laboratory and GP services makes your health journey seamless and extremely efficient.

This service is not included in the price of the test, it is charged separately, should you wish to book it.

Will I have a general explanation of my results?

Yes, our doctors put a huge amount of effort into your online Health Dashboard, which will have explanations of what each biomarker is, the normal reference ranges and what it means if you are outside of them.

QUICK AND ACCURATE RESULTS DIRECT FROM THE LABORATORY.

We partner with regulated laboratories and accredited clinics that manufacture their own approved home sample collection kits. Your results are looked after by our fantastic clinical governance team and a super-talented biomedical science team.

When you book your test with us - you book directly with the lab. This means accuracy and responsible duty of care, direct access to the provider and extremely fast turnaround times.