In short
- The thyroid sets the pace of metabolism through the hormones T4 and T3.
- TSH is the most sensitive measure of thyroid function.
- Thyroid symptoms are non-specific and overlap with other conditions.
- A thyroid test starts with TSH, supplemented by Free T4.
What you can measure
Not every cause is visible in blood. These are the values that most often explain something.
Recommended test
Aanbevolen bij moeheid waarbij u de schildklier wilt uitsluiten
Thyroid function
2 markersTSH is de meest gevoelige maat voor de schildklierfunctie en wordt beoordeeld samen met Vrij T4. Deze combinatie kan de schildklier als oorzaak van uw moeheid in beeld brengen of juist buiten beeld zetten.
- Personal assessment by a registered doctor
- Clear laboratory report, in plain language
- No referral needed
- 800+ blood draw locations
€69
Plus 29,- blood draw fee per order, free from 225,-.
Prefer something else?
- Fatigue & Sleep€189· Meet naast de schildklier ook ferritine, vitamine B12, foliumzuur, vitamine D, cortisol, magnesium en het bloedbeeld. Aanhoudende moeheid heeft zelden één oorzaak, en niet iedere oorzaak is zichtbaar in bloed.
- Bloodworks Premium€399· Bevat de schildklierwaarden en daarnaast bloedbeeld, lever, nier, hart, bloedsuiker, het ijzerpaneel en de vitamines en mineralen. Voor wie moeheid in één afname breed wil laten onderzoeken.
What does the thyroid do?
The thyroid is a butterfly-shaped gland in the neck that produces thyroid hormones: primarily T4 (thyroxine) and the active form T3. These hormones control metabolism, the rate at which cells burn energy. A well-functioning thyroid keeps that process in balance. An underactive or overactive thyroid disrupts it.
The thyroid is controlled by TSH (thyroid-stimulating hormone), released from the brain (pituitary gland). TSH is therefore the most sensitive measure of thyroid function: if the thyroid produces too little hormone, TSH rises to make the gland work harder.
A high TSH indicates an underactive thyroid (hypothyroidism); a low TSH indicates an overactive one (hyperthyroidism).
Thyroid symptoms: why so difficult to recognise?
An underactive thyroid produces complaints that come on slowly and insidiously:
- fatigue
- feeling cold
- a slow heart rate
- weight gain
- dry skin
- constipation
- muscle aches
- difficulty concentrating
Because the symptoms worsen gradually and overlap strongly with other conditions, including stress, sleep deprivation, and depression, hypothyroidism is regularly identified late.
What to measure in a thyroid test?
The foundation is TSH. If TSH is abnormal, Free T4 (FT4) is involved: this gives insight into how much thyroid hormone is actually circulating in the blood. For a more complete picture, particularly with suspected autoimmune conditions such as Hashimoto's, thyroid antibodies (TPO antibodies) are also relevant.
At Bloodworks, the Thyroid function package measures TSH and Free T4, the two core values for assessing thyroid function.
Want to have your thyroid tested?
The Thyroid function package measures TSH and Free T4, the core values of your thyroid.
Measuring fatigue: looking beyond the thyroid
Persistent fatigue rarely has a single cause. Alongside the thyroid, these markers may be relevant in the context of fatigue complaints:
- ferritin (iron stores)
- vitamin D
- vitamin B12
- cortisol
Those who want to investigate fatigue seriously would do well to combine multiple markers. The Bloodworks Fatigue & Sleep package is designed for this, eight markers in a single blood draw.
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