Thyroid function

Do you also sometimes feel tired, often feel cold, suffer from mood swings, weight gain or low energy? Unfortunately, we all suffer from these things at times, but they can also be symptoms of a slow-working thyroid.

When a thyroid gland is working too fast, you can experience symptoms such as: poor sleep, trembling hands, excessive sweating, weight loss, intestinal problems, shortness of breath and/or fatigue.

The thyroid produces the hormone Thyroxine (T4) and releases it into the blood. This hormone helps your body with metabolism and heat regulation, among other things. It therefore has an important role to play in your body.

In order to detect a thyroid that is working too slowly or too quickly in good time, it is advisable to check the thyroid function. If thyroid disorders are not treated (in time), they can lead to health problems such as cardiovascular disease, hyperactivity and depression.

This test will give you insight into your thyroid function.

The markers tested are:

  • TSH;
    • An important hormone-producing gland in the brain (pituitary gland) ensures that the right amount of thyroid hormone is produced.
  • fT4 (free T4)
    • The free, active form of the hormone Thyroxine (T4).
  • icon It is completely anonymous;
  • icon You can always come to us:
  • icon You do not have to go directly to a healthcare provider;
  • icon The test is as reliable as the one used in hospitals;
  • icon Our clinical chemist will assess your results and give you tailored advice;

Markers and consequences


The thyroid gland is a butterfly-shaped gland in the neck region with an important function in the body. The thyroid gland is responsible for the proper functioning of the body's metabolism and growth. The thyroid gland releases thyroid hormones that influence these processes in the body.



TSH is produced by the pituitary gland, a major hormone-producing gland in the brain. TSH ensures that the right amount of thyroid hormone (T4 and T3) is always produced. Thyroid hormones regulate energy and metabolism in the body.

In general, increased TSH and decreased fT4 means a sluggish thyroid, decreased TSH and increased fT4 means a fast-working thyroid.


fT4 (freeT4)

T4, also called thyroxine, is one of the two hormones produced by the thyroid gland. The other hormone produced by the thyroid is the T3 hormone (triiodothyronine). If a thyroid dysfunction is suspected, TSH and free T4 (fT4) are determined in the first instance.

In the blood, T4 is largely bound to proteins. Only free (unbound) T4 is effective as a hormone in the body, this is called fT4 (free T4). Free T4 is the part of T4 that flows freely in your blood and is not bound to protein.

If a thyroid dysfunction is detected, or if the fT4 and TSH are not sufficiently clear, T3 is also determined. T3 is the active thyroid hormone. In particular, it affects many organs and processes in the body such as metabolism, energy consumption, growth and brain development. In the blood, almost all T3 is bound to proteins.



When too few thyroid hormones are made, the pituitary gland receives a signal to make TSH, which then stimulates the thyroid gland to produce thyroid hormones. Conversely, when there is too much thyroid hormone in the blood, the pituitary gland will receive a signal to make less TSH, and the thyroid gland will make fewer hormones.

Most thyroid abnormalities result in either too little or too much thyroid hormone being produced. This leads to many physical symptoms.


Do you have a slow-working thyroid?

A slow-working thyroid gland is also known as 'hypothyroidism'. If your thyroid gland is working too slowly, too little thyroid hormone enters your bloodstream and your metabolism slows down.

The most common complaints:

  • Low energy, sluggish or tired;
  • Easily feel cold;
  • Weight gain;
  • Shortness of breath;
  • Hair loss;
  • Dry skin;
  • Heart beats slower;
  • Thicker face or eyelids;
  • Mood swings or depression;
  • Irregular periods;
  • Voice changes;
  • Thyroid gland feels bigger.

There is little you can do about it. You will need to take medication to restore sufficient thyroid hormone. Therefore, contact your doctor.

If thyroid disorders are not treated (in time), they can lead to health problems such as cardiovascular disease and depression, among others.


Do you have a thyroid that works too fast?

A thyroid that works too fast is also called 'hyperthyroidism'. If your thyroid is working too fast, it is making too much T4 hormone. This makes the metabolism in your body go faster.

The most common complaints:

  • Palpitations;
  • Excessive sweating, often hot;
  • Shaking/ trembling;
  • Fatigue;
  • Restless bowels;
  • Weight loss (despite eating enough);
  • Bulging eyes, larger eyes, less sharp vision or your eyes feel painful;
  • Thyroid gland feels bigger.


There is little you can do about it. There are three ways to treat an overactive thyroid: medication, radioactive iodine or surgery. Therefore, contact your doctor.

If thyroid disorders are not treated (in time), they can lead to health problems such as cardiovascular disease and hyperactivity, among others.

Our Thyroid Function Test

To find out whether you have a thyroid that is working too slowly or too quickly, How Are You Diagnostics offers the Thyroid Function Self-Test.

The Thyroid Function Test offered by How Are You Diagnostics is the same laboratory test as carried out by hospital laboratories.

We distinguish ourselves by offering the majority of our tests via a self-test kit. This means that you can have our tests delivered to any postal address, after which you can take the sample for the chosen test yourself at any time. So you can take your sample at home, just like with a self-test/home test.

For some markers such as TSH, you can also buy a self-test from a chemist or pharmacy. For these, you put a drop of blood on a special strip and the result is displayed immediately. The self-test gives you an impression of the level of the marker in question in the blood.

With a self-test you have to interpret the result yourself, which is difficult if you are not qualified to do this like a clinical chemist. It is more reliable to perform the test in a laboratory with the appropriate equipment and have the result determined by a clinical chemist.

Similar tests from your GP or hospital are often twice as expensive. You also have to make an appointment and go to the appointment to do a blood test

How does it work?

Wij hebben speciale thuis testen ontwikkeld zodat jij ze gemakkelijk thuis, op ieder gewenst moment, kunt uitvoeren. Het geeft snel zekerheid en helpt belangrijke vragen te beantwoorden.

Om de test uit te voeren maakt u gebruik van onze How Are You Diagnostics App. Deze App is te downloaden in de App Store en de Google Play Store. Hierin maakt u een persoonlijk account aan, koppelt u de test aan uw account en wordt u stap voor stap uitgelegd hoe u de test uitvoert. Verstuur de test en ontvang het resultaat in uw persoonlijke account van onze beveiligde App. Het is niet mogelijk om het testresultaat te ontvangen zonder het gebruik van de App.

Verstuur de test zo snel mogelijk na afname; dit kan gratis via een reguliere PostNL brievenbus.

Tijdens het gehele proces gaan we vertrouwelijk met uw gegevens om. Na ontvangst in het laboratorium ontvangt u binnen 5 werkdagen de resultaten in de App. U ontvangt een melding als het resultaat beschikbaar is.

Content and step-by-step plan 

Inhoud van de test:

  • informatiebrief;
  • vingerprikset (alcoholdoekje, vingerprikker, gaasje en een pleister);
  • afnamebuisje;
  • retouroplossing (RigidSafetyBag en een gefrankeerde retourenvelop).

De afname instructies zijn te vinden in de How Are You Diagnostics App.


Testen in vier stappen:

  1. Download de How Are You Diagnostics App
    Download onze App in de App Store (iOS) of Google Play Store (Android).
    Registreer een account of log in.
  2. Doe de test
    Scan de code van de buis/container of voer deze handmatig in.
    Start de afname.
  3. Verstuur de test
    Verstuur de test naar ons laboratorium.
  4. Ontvang het testresultaat
    Ontvang en bekijk het resultaat van de test in de App.