Full thyroid blood test with anti-TPO antibodies

First line

Full thyroid blood test with TSH, free T4, free T3 and anti-TPO antibodies. It looks at two things: how the gland is working, and whether there are signs of thyroid autoimmunity, the most common cause of hypothyroidism.

No prescription or appointment needed

Results in 1-2 working days

Includes: TSH · Free T4 · Free T3 · Thyroid peroxidase antibodies. See what each one measures

What it is for

This blood test is designed for a first, broad assessment of thyroid function. The hormones show whether the pattern is compatible with hypothyroidism, hyperthyroidism or thyroid function within the reference range.

Anti-TPO antibodies answer a different question: whether there are signs that an abnormality may have an autoimmune origin, such as Hashimoto's thyroiditis. These antibodies can be positive before the hormones change, although a positive result on its own does not automatically diagnose the problem or mean that it has to be treated.

Knowing thyroid function and antibodies from the same sample makes it easier to place an abnormal result in context and to decide, at the medical assessment, whether follow-up or further tests are needed.

When it is recommended

Symptoms of hypothyroidism: tiredness, hair loss, dry skin, constipation or feeling the cold
Symptoms of hyperthyroidism: nervousness, palpitations, weight loss or feeling the heat
Weight changes without a clear explanation
When a general blood test has shown an abnormal TSH
A family history of thyroid disease or Hashimoto's thyroiditis
When trying for a pregnancy, if there is a relevant history, symptoms or a previous abnormal TSH

Clinical comment

This is the profile we have designed for a first look at a thyroid that has not yet been assessed. It brings together the tests that answer the two initial questions: how the gland is working, and whether there is a common autoimmune cause.

Free T3 adds little in the usual assessment of hypothyroidism, because it can stay normal even when TSH and free T4 are already abnormal. It is included because it is useful when TSH is low: it can reveal hyperthyroidism in which T3 is raised while free T4 is still normal.

Among the antibodies, anti-TPO is included because it is the first-line marker for investigating possible autoimmune thyroiditis. Thyroglobulin antibodies can add information in some cases, but they perform less well in a first assessment. They are included in the thyroid blood test with key micronutrients, designed for a more extensive review.

Dr. Antonio Mas

What is tested

TSH: The hormone the pituitary gland uses to regulate the thyroid. It is usually the first test to change and guides the rest of the investigation.
Free T4: The main hormone produced by the thyroid, measured in its free fraction. It shows how much thyroxine is available in the blood.
Free T3: The thyroid hormone with the greatest activity in the tissues. It is particularly useful when TSH is low and possible hyperthyroidism is being investigated.
Thyroid peroxidase antibodies (anti-TPO): Antibodies against thyroid peroxidase. Their presence supports an autoimmune origin, such as Hashimoto's thyroiditis, although they can also appear in people with normal thyroid function.

How to prepare

No fasting is required. If you already take levothyroxine, have the sample taken before that day's dose. If you take biotin supplements, which are common in hair and nail products, stop them 48 hours before, because they can interfere with several thyroid tests.

You can add

Without another needle. It is offered when you order, so you do not have to decide now.

General blood testA general blood test with full blood count, glucose, cholesterol and kidney and liver function: the basic parameters included in any general check-up.+€59.00
General + nutritional blood testEverything in the general blood test (anaemia, kidneys, liver, cholesterol and glucose) plus iron stores, vitamin D, vitamin B12 and folic acid. It is the broadest add-on: it covers the general and the nutritional in one go.+€129.00
Coeliac disease antibodiesMeasures the antibodies used to investigate coeliac disease; for a reliable result, it must be done while you are still eating gluten.+€39.00

Related blood tests

We have other profiles in Thyroid with more or fewer tests:

The most comprehensive is not always the most useful. This is the one we recommend to start with; the others cover specific situations.

What it is based on

Clinical guidelines place TSH as the first test of thyroid function and add free T4 when TSH is raised. When TSH is low, they recommend completing the assessment with free T4 and free T3. Measuring anti-TPO helps identify a possible autoimmune origin when there is a compatible abnormality.

American Thyroid Association · Thyroid 24(12):1670-1751
Guidelines for the Treatment of Hypothyroidism
Establishes TSH as the best single test for assessing thyroid function in most outpatient situations.
European Thyroid Association · Eur Thyroid J 2(4):215-228
ETA Guideline: Management of Subclinical Hypothyroidism
When TSH is raised and free T4 is normal, recommends repeating both together with thyroid peroxidase antibodies.

Protocol designed by Dr. Antonio Mas, specialist in Endocrinology and Nutrition, Spanish medical licence no. 080846289, and reviewed in September 2026.

This blood test is a standardised protocol and does not replace a medical consultation. If you have symptoms, a known condition or a complex clinical situation, speak to your doctor.