Insight into your TSH level.
TSH is the hormone from the pituitary gland that signals the thyroid, and the usual first step in thyroid testing. A measurement gives insight into how strongly your body is stimulating the thyroid.
Also known as: thyroid stimulating hormone, thyrotropin, thyroid function
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Background
What is TSH?
TSH (thyroid stimulating hormone) is not made by the thyroid itself but by the pituitary gland, a small gland at the base of the brain. TSH is the signal with which the body puts the thyroid to work: the more TSH, the more strongly the thyroid is stimulated to produce thyroid hormone (mainly T4). The pituitary continuously senses how much thyroid hormone is circulating in the blood and adjusts its TSH release accordingly, much like a thermostat.
Because of that feedback loop, TSH moves as a mirror image of the thyroid: with a slower thyroid, TSH rises because the body has to push harder, and with a faster thyroid, TSH falls. Since TSH often changes before anything is visible in the thyroid hormones themselves, it is the usual first step in thyroid testing. A single measurement is a snapshot, not a diagnosis: an abnormal result is often followed by a repeat measurement or additional testing, such as Free T4.
In brief
From the pituitary
A signalling hormone, not from the thyroid itself
First step
The usual starting point of thyroid testing
Mirror image
High fits a slower, low fits a faster thyroid
Alongside Free T4
The combination gives the most complete picture
Common reasons to test
When can insight into your TSH be valuable?
Below are some situations in which measuring TSH can provide insight.
Insight into your thyroid signalling
A TSH measurement gives a snapshot of how strongly your body is stimulating the thyroid, the usual starting point of thyroid testing.
With questions about energy or weight
Unexplained changes in energy, weight or sensitivity to temperature are sometimes associated with the thyroid.
With thyroid conditions in the family
Thyroid conditions run in families. With a family history, people more often choose periodic testing.
Before and during a wish to conceive
Thyroid function plays a role in fertility and pregnancy. A test may form part of preconception checks.
For follow-up of thyroid medication
Those taking thyroid medication have TSH measured periodically to see whether their treatment remains stable.
For general health monitoring
TSH is one of the most commonly measured markers in self-requested blood tests, as a basic check of thyroid function.
What your result means
TSH too high or too low: what does your result mean?
TSH is measured in milli-units per litre (mU/L). The laboratory states the reference values that apply there alongside your result. Important to know: TSH moves as a mirror image of the thyroid and can also be temporarily shifted, for example after a period of illness. A single measurement is a snapshot, not a diagnosis.
A low value
A reduced TSH can fit with a faster working thyroid: so much thyroid hormone is circulating that the pituitary needs to stimulate less. Other factors sometimes play a role as well, such as early pregnancy, certain medication or a temporary inflammation of the thyroid. Free T4 is then often measured in addition. Our doctor provides explanation and context with your result, so you can discuss it with your GP if you wish.
A normal value
A TSH within the laboratory's reference values gives a reassuring picture of the signalling of the thyroid. For most questions that is sufficient. Bear in mind that symptoms are rarely explained by a single value: with persistent complaints, a repeat measurement at a later moment or broader testing may still be worthwhile.
An elevated value
An elevated TSH often fits with a slower working thyroid: the body has to push harder to obtain enough thyroid hormone. Mild elevations are common and regularly temporary, for example after illness. With an abnormal result, a repeat measurement after several weeks, often together with Free T4, is a customary approach. Our doctor explains what your value means.
How we interpret your result
Our doctors interpret your TSH against the laboratory's reference values and your personal context, such as symptoms, medication use, a possible pregnancy and earlier results. You receive a report in plain language, as a starting point for your own insight or a conversation with your healthcare provider.
Related tests
Often combined with TSH.
A single marker gives one perspective. For a broader picture you can combine TSH with a theme package or related markers.
+ €29 blood draw fee per orderFree from €225
Frequently asked questions
Everything you want to know
Do I need to fast for a TSH test?
No, you do not need to fast for TSH. You can have blood drawn at any time of day. TSH does follow a mild daily rhythm, but for most questions the timing of the blood draw makes little difference.
What is the difference between TSH and Free T4?
TSH is the signalling hormone from the pituitary gland in the brain. Free T4 is the hormone the thyroid itself produces. TSH shows how strongly the body is stimulating the thyroid, Free T4 shows what the gland delivers. The two are almost always assessed together.
Why is TSH the first step in thyroid testing?
The pituitary responds sensitively to small changes in the amount of thyroid hormone. As a result, TSH often changes while Free T4 is still normal. A TSH measurement is therefore the usual first step; depending on the result, additional testing follows.
Is TSH alone enough to assess my thyroid?
For a first impression, usually yes: TSH is the customary first step. With an abnormal TSH, persistent complaints or a known thyroid condition, Free T4 is almost always measured as well. If you want both values in one go, have a look at the Thyroid function package.
Which is the better value: TSH on its own or the Thyroid function package?
That depends on what you want to know. TSH on its own costs €40. The Thyroid function package contains TSH and Free T4 together for €69, while ordered separately those two come to €80. The €29 blood draw fee is charged only once per order and is waived from €225, so it works out the same either way. If you want both values, the package is the better value; if you only want to know your TSH, the single test is the cheapest option.
Does my medication affect the result?
Yes, some substances can affect the value or the measurement, including thyroid medication itself, biotin supplements, lithium, amiodarone and corticosteroids. Please tell us about your medication and supplements so our doctor can take this into account during interpretation.
How soon after a change in thyroid medication can I retest TSH?
After a change in thyroid medication, retesting usually takes place only after around 6 to 8 weeks. Retesting sooner is of little value, because the feedback loop needs time to stabilise.
What do I do with my result?
You receive a PDF report with your value and a personal explanation from a doctor. What you do with it, such as discussing it with your GP, remains entirely your choice. The report is written in medical language and can be shared with your healthcare provider.
In the Health Guide
Read more about this value
Ready for insight into your TSH level?
You receive your TSH level including personal explanation from a doctor, typically within 2 working days. No referral required.
Order TSH →Want to test multiple markers at once?
Combine TSH with other markers via Bloodworks Select. The blood draw and collection fee is charged once per order, and is waived from €225.
40,-
+ €29 blood draw fee+ €29 blood draw fee per order