The baseline value: TSH
TSH is not a thyroid hormone but the signal sent by the pituitary gland to the thyroid. It works like a thermostat: if the thyroid produces too little, the TSH rises; if it produces too much, the TSH falls. That is why TSH is so sensitive – and why almost every work-up starts with it.
A single abnormal TSH value, however, is not yet a diagnosis. Acute illness, stress, medication and even the time of day affect it. Before we start any treatment, we therefore usually confirm a suspicious value with a second measurement.
At a glance
- Laboratory: TSH as the baseline value, plus fT3 and fT4 as well as antibodies depending on the question
- Ultrasound: size, structure, blood flow, nodules, neck lymph nodes – radiation-free
- Fine-needle aspiration: cell sampling under ultrasound guidance, a few minutes, usually without anaesthesia
- Scintigraphy and radioiodine therapy: in cooperation with a nuclear medicine centre
- Duration: initial work-up with consultation, blood draw and ultrasound usually 30 to 45 minutes
- Please note: on the day of your examination, take levothyroxine only after the blood draw
The in-house laboratory
We measure thyroid values directly on site. This not only shortens the wait for your results, but also allows us to re-measure an individual value at short notice if the picture does not add up.
Which values make sense depends on the question at hand. A routine check for well-controlled hypothyroidism requires considerably less than an initial work-up for suspected autoimmune disease.
The most important laboratory values
| Value | What it shows | When we measure it |
|---|---|---|
| TSH | Control signal from the pituitary gland | always |
| fT4 (free thyroxine) | Storage hormone in the blood | if TSH is abnormal |
| fT3 (free triiodothyronine) | Active hormone | mainly if hyperthyroidism is suspected |
| TPO antibodies | Indicator of Hashimoto’s thyroiditis | for hypothyroidism, trying to conceive, unclear results |
| Tg antibodies | Second autoimmune marker | as a supplement |
| TRAb | Indicator of Graves’ disease | for hyperthyroidism |
| Thyroglobulin | Monitoring marker after thyroid cancer | in follow-up care |
The table is no substitute for an individual assessment. Which values make sense in your case is something we discuss at your appointment.
The ultrasound
Ultrasound shows what the laboratory cannot: how large the thyroid is, what its tissue looks like, whether nodules are present and how well it is supplied with blood. In Hashimoto’s, for example, the tissue typically appears darker and more irregular than in a healthy thyroid.
The examination takes a few minutes, is painless, involves no radiation and can be repeated as often as needed. You lie relaxed with your head slightly tilted back, and a warm gel provides the contact with the probe.
Fine-needle aspiration
Nodules in the thyroid are common and benign in well over ninety percent of cases. However, if a nodule shows certain features on ultrasound or exceeds a certain size, we investigate it more closely with a fine-needle aspiration.
Under ultrasound guidance, a very thin needle – thinner than for a blood draw – is used to take a small sample of cells, which is then assessed in the laboratory. The procedure takes a few minutes, usually requires no anaesthesia, and you can carry on with your day as normal afterwards.
Frequently asked questions
Does fine-needle aspiration hurt?
Most patients describe it as less unpleasant than a blood draw. The needle used is very thin, and the puncture takes only seconds. A slight feeling of pressure in the neck may remain for one to two days.
How often should I have my thyroid checked?
That depends on your results. For stable, well-controlled hypothyroidism, an annual check is usually sufficient. After a dose change, we re-measure after six to eight weeks. We monitor nodules at intervals of six to twenty-four months, depending on size and ultrasound appearance.
Why was only TSH measured in my case?
Because TSH is the most sensitive single value. If it is within the normal range and you have no symptoms, additional hormone values generally provide no further insight. As soon as the TSH deviates or symptoms are present, we extend the testing.