Order a thyroid test: TSH, FT4 and FT3

A thyroid test gives you a snapshot of how your thyroid is working right now. TSH is usually the first value doctors look at, but by also measuring the active hormones free T4 and free T3, you get a clearer picture of thyroid activity.

For busy professionals, a thyroid blood test like this can be an efficient first step towards understanding symptoms such as fatigue, weight changes or low energy. It is not a diagnosis, but preventive insight you can discuss with a doctor.

This test may suit people who:

• have symptoms that might relate to the thyroid, such as fatigue, sensitivity to cold or heat, or weight changes
• have a family history of thyroid conditions
• previously had an abnormal value and want to recheck it
• want to have their thyroid tested as part of a broader health check

This panel measures three thyroid markers in your blood:

• TSH (thyroid-stimulating hormone): produced by your pituitary gland; it signals the thyroid and is often the first marker to shift when things change.
• Free T4 (thyroxine): the main hormone your thyroid produces, which is converted into the more active T3 in tissues.
• Free T3 (triiodothyronine): the more active hormone that directly influences your metabolism and energy at the cellular level.

You can read more on the pages about TSH and free T4.

The combination of values says more than a single number. An elevated TSH with a low free T4 value may point to an underactive thyroid, while a suppressed TSH with a raised free T4 or free T3 may fit an overactive thyroid.

Subclinical patterns, where TSH is slightly abnormal but T3 and T4 remain within range, can also become visible. Together these markers offer context you can discuss with your healthcare provider.

For this test, blood is drawn at a certified sample point (afnamepunt). There are 700+ locations across the Netherlands, which you choose yourself after ordering, at a time that suits you.

You do not need to see your GP first: this is a blood test without a referral. The draw is done by trained staff and usually takes only a few minutes. Unlike a home self-test, your blood is analysed in a certified lab.

This test can be useful when:

• you experience symptoms you cannot quite place, such as ongoing fatigue, palpitations or changes in your weight
• you suspect an underactive thyroid and want to investigate it
• you have a known thyroid condition and want to track your levels
• a previous blood test showed a borderline TSH value

Would you like to test your thyroid as a baseline? This panel can be a useful starting point for that too.

Each marker appears with your value and its reference range. TSH, free T3 and free T4 are best viewed together, as the relationship between them provides context. For example, a TSH at the upper end of the range with a free T4 at the lower end may tell a different story than either number alone.

What counts as a healthy value varies by lab, age and timing, so a number on its own says little. Only a doctor can properly interpret your result.

For this thyroid test you usually do not need to fast. You can pick a time that fits into your day.

Do you use thyroid medication or other hormones? Then ask your doctor whether and when it is best to measure, as this can affect your result.

Your results are available online within a few working days. You see your values, their reference ranges and a clear explanation. If a marker falls outside the expected range, this is highlighted.

Every blood test result includes a professional assessment from a BIG-registered doctor. For treatment decisions, discuss your results with your GP.