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Dr Marcus de Brun. Rush Family Practice

Medical guide

Additional treatments

Thyroid tests explained

Thyroid tests explained

There are various types of thyroid examination allowing thyroid diseases to be detected or monitored.

How will my thyroid be examined?

Palpation is the basis of the thyroid examination. The thyroid is only palpable if it is not functioning correctly.
The thyroid is a small, mobile gland located at the base of the neck. When it is palpable, it can be felt rising when the person swallows their saliva or food.
Palpation provides accurate information about its consistency (hard or soft), sensitivity (painful or not), shape (regular or not) and the presence of nodules (lumps or not).
It is a very simple way of detecting a large number of thyroid diseases, such as goitre (swelling), which is a sign of an enlarged thyroid or the presence of nodules.

What is the blood test used for?

The blood test allows the level of different thyroid hormones to be measured.
It provides information about the thyroid's functional capacity (is it producing enough hormones or not?) The main test used to detect thyroid disorders is the test to measure levels of TSH, which controls the thyroid.

  • A normal TSH level indicates correct thyroid function
  • A high level shows that the thyroid is underactive
  • A level lower than normal reveals an overactive thyroid

This TSH measurement alone is enough to give information about thyroid function, because it is more precise and more quickly disrupted than thyroid hormone levels. It can also be used to assess the efficacy of any treatment initiated.
The assessment may also involve measuring antibodies in order to better classify hypothyroidism or hyperthyroidism, and in some cases a thyroxine or T4 test is performed.

Why do I need an ultrasound?

This technique is completely painless and involves running an ultrasound probe over the base of the neck, around the gland.
Ultrasound gives morphological information about the volume and structure of the thyroid. It also allows doctors to check for the presence of nodules or cysts, and to assess their volume and whether their content is solid or liquid.
A thyroid ultrasound is a completely painless examination.
The ultrasound waves used are not dangerous. There are no contraindications or side effects.

I have to have a thyroid uptake scan— what is it?

This examination is often performed in cases of hyperthyroidism and is used to study your thyroid function. It is an examination based on the thyroid gland's ability to absorb iodine. A small quantity of radioactive iodine (or marked technetium) is injected into a vein in the crook of the elbow.
The nodules secreting hormones use the iodine and therefore pick up the radioactive iodine that is injected. A special camera shows this radioactivity concentrated in the thyroid and/or nodules, and produces an image of the thyroid. The image can show areas of hyperfixation (which indicate thyroid overactivity, as in the case of so-called "hot" nodules) or areas of hypofixation.
Note that injecting this low dose of radioactive iodine is not dangerous for your body, even if you are allergic to iodine. Scintigraphy is, however, contraindicated during pregnancy.
The availability of ultrasound and fine needle aspiration biopsy means that scintigraphy is becoming less and less commonly used in the exploration of nodules. Nevertheless, it may be prescribed in some cases. This examination is currently used only when TSH is low and doctors are looking for an overactive toxic nodule. The examination is not useful for small nodules under 9 mm in size, as these are not visible.
This examination is not advised for pregnant women or those who could be pregnant.
The contrast medium (iodine product) causes a warm sensation when it is injected. It can trigger an allergic reaction.

I have to have a biopsy — why?

A puncture, or fine needle aspiration biopsy, is performed in order to confirm the diagnosis of whether one or several nodules are benign or malignant. This examination is often carried out under ultrasound in order to better target the nodule showing suspicious characteristics in the ultrasound scan. It involves extracting a few cells directly from the nodule using a very fine needle. The biopsy is relatively painless. The cells extracted are then spread onto a plate and analysed by a thyroid cytology specialist.
This examination is practically painless. The discomfort is comparable to that felt during a blood test. The biopsy is performed using an extremely fine needle. Local anaesthetic is not necessary.
There is no risk of complications.

In order to compare different hormone levels and their progression over time, it is important to always perform biological tests in the same medical laboratory.

Your doctor or a member of the medical team will inform you of the procedure for each of the examinations. They can answer any questions you may have. Do not hesitate to let them know about any queries or worries you may have.

Keep your test results and remember to bring them with you to your next appointment or to any future examinations.

Publication date:   11/29/11

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