Thyroid nodules

Thyroid nodules are one of the most common changes in the thyroid gland. In most cases they are harmless and go unnoticed at first, as they often do not cause any discomfort. It is only when the nodules start to grow that they may lead to a feeling of pressure or cause difficulty swallowing.

Thyroid nodules are relatively common and increase with age, with women being more prone to changes in the hormone-producing gland than men. Patients should be aware that a thyroid nodule is not the same as a struma (or goitre), but patients with a goitre are more susceptible to nodules forming in the area of the thyroid gland.

Although largely harmless, in some cases thyroid nodules may result in a diagnosis of thyroid cancer, so it is advisable to have a nodule on the thyroid gland examined and treated if necessary.

How are thyroid nodules formed? 

Thyroid nodules are formed when cells in individual areas of the thyroid gland multiply excessively and/or become enlarged. The nodules are characterised by their varying levels of growth: while some only to a limited extent, others continue to increase in size. It is however possible for a nodule on the thyroid gland to go away on its own.

Symptoms

At first, each nodule in the thyroid gland is small. Some nodules will remain small, while others continue to grow and eventually reach a size that causes the patient to have difficulty swallowing. It may also lead to hoarseness, forced clearing of the throat, or a general feeling of pressure in the throat.

Furthermore, the nodule itself may become sensitive to pressure, making it painful. This is particularly likely when the nodule is formed in connection with a goitre, meaning that the entire thyroid gland is already enlarged.

In addition, a hot nodule can cause symptoms indirectly, as it contributes to the thyroid gland producing excessive quantities of thyroid hormones. In such cases, the same symptoms emerge in a similar way as with an overactive thyroid (hyperthyroidism).

Causes

Possible causes of thyroid nodules include the following conditions:

  • benign tissue formation in the thyroid gland, such as adenomas (benign growths that develop from the uppermost layer of the thyroid tissue).
  • cysts (fluid-filled cavities), which often occur when the thyroid tissue begins to grow.
  • thyroid cancer
  • metastases (secondary tumours) of other cancers in the body, which form in the thyroid gland. These can lead to the development of malignant thyroid nodules (such as breast, lung or colon cancer).
  • throat tumours (local tumours in the throat area), which can grow into the thyroid gland.

Diagnosis

Thyroid nodules are often discovered by chance during a check-up of the neck area. It is therefore important to consult a doctor if you have the feeling that your own thyroid gland has changed or become enlarged. This is because a medical examination is necessary to determined what kind of nodules you have and whether you require treatment.

Regular blood tests including monitoring of thyroid values can help to detect thyroid nodules at an early stage. However, since these nodules often do not coincide with hormonal changes, it is advisable to have the thyroid gland examined by a doctor from time to time, even when the blood levels are normal.

If a thyroid nodule is suspected, the doctor will begin by ascertaining the patient’s medical history. They will also ask for information such as when the patient first noticed the changes in their thyroid gland, whether the nodule has grown since then, and whether the patient has any symptoms (and if so, in what form). After that, the doctor will take measures to distinguish between benign and malignant nodules.

The medical history is followed by a physical examination. The doctor will palpate the thyroid gland and lymph nodes (which are part of the body’s defence system), paying particular attention to possible malignant changes, such as a noticeably raised surface of the nodule or inadequate displacement of the nodule when swallowing.

This is followed by an ultrasound examination, also called a sonography. This usually identifies nodules measuring three millimetres or more. If the nodule is larger than one centimetre or if a previous blood test has shown a hormonal imbalance, scintigraphy is the medical method of choice. This examination method allows the surgeon to classify the nodule and determine if it is hot or cold.

If the result of the scintigraphy confirms that it is a cold thyroid nodule, a tissue sample ( biopsy) will be taken to rule out the possibility that the nodule is malignant, i.e. contains cancer cells. For this purpose, the doctor uses a very thin needle to pierce the nodules through the skin under ultrasound control (fine-needle aspiration cytology or FNAC) and extracts some of the cells. These are then examined under the microscope by a pathologist for the presence of cancer cells (tissue-based diagnosis).

Treatment

Small, benign nodules are usually not treated. However, patients with a nodule in the thyroid gland are advised to have their thyroid examined regularly by a specialist. This is the only way to detect potential changes in the nodule in good time – and ensures that even a change in thyroid function does not go unnoticed for too long.

There are three main treatment options for a thyroid nodule.

  • Medicinal therapy: This is only an option for small, cold nodules. The patient is given thyroid hormones, usually in combination with iodine. The purpose of the medication is to inhibit the growth of the glandular tissue and thus stop the nodule from progressing further. In the case of larger, painful nodules, however, medication is usually not highly effective, which is why it is avoided from the outset.
  • Nuclear medicine treatment: Here, the patient is administered radioactive iodine, which then deposits into the hormone-producing thyroid cells and destroys them. However, the use of radioiodine therapy is only effective in treating benign, hot thyroid nodules. It cannot be used to treat a cold nodule because cold nodules do not absorb the radioactive iodine.
  • Surgery: An operation can be carried out to remove just the thyroid nodule itself, just the thyroid lobe (hemithyroidectomy) or the entire thyroid gland (subtotal thyroidectomy). Various surgical techniques can be used here. The procedure may be performed via open surgery (i.e. by making an incision in the neck) or by laparoscopy (minimally invasive endoscopic surgery). Surgery is always advisable if the nodule in the thyroid gland is suspected of being cancerous or if the thyroid gland is already severely enlarged (goitre).

Aftercare

With the right therapy and appropriate, regular medical check-ups, benign thyroid nodules can usually be cured, and malignant thyroid tumours also have a good prognosis.

It has also been proven that a balanced diet and an adequate intake of iodine can counteract the formation of thyroid nodules (as well as other thyroid disorders).

Thyroid surgery always affects the patient’s hormonal balance – no matter how much thyroid tissue has to be removed. Here, the following principle applies: the lower the quantity of tissue removed, the lower the drop in hormone levels. The higher the quantity of tissue removed, the lower the risk of new nodules forming or changes in the thyroid gland.

Aftercare for patients who have undergone thyroid surgery includes the optimal (medicinal) adjustment of thyroid hormones and the best possible prevention of relapses (also known as recurrent prophylaxis). The medication administered depends on the type of thyroid nodule and the size of the remaining thyroid gland. If the thyroid gland has had to be completely removed, life-long hormone replacement therapy with thyroxine is necessary.

FAQs

What is the difference between a cold nodule and a hot nodule?

The differentiation of thyroid nodules into ‘cold’ and ‘hot’ pertains to whether the respective nodule produces thyroid hormones. Cold nodules produce few or no hormones, while hot nodules produce more thyroid hormones than the rest of thyroid tissue. These are much rarer than cold nodules.

Where do the terms “hot” and “cold” come from?

The names of the two types of nodule derive from scintigraphy, a nuclear medical examination that makes it possible to distinguish between hot and cold thyroid nodules. In the course of a scintigraphy, the patient is injected with a fluid containing radioactive iodine, which enters the thyroid gland via the bloodstream. A thyroid nodule that produces hormones (a hot nodule) requires a lot of iodine. This means that the radioactive iodine accumulates more strongly in a hot nodule. There, it decomposes by emitting radioactive radiation, which can be made visible using a special camera. The area in question is picked up by the camera as a yellow to red zone, i.e. in ‘hot’ colours. In contrast, tissue in which little or no hormone production takes place hardly absorbs any of the radioactive iodine – the camera shows these tissue areas in blue to violet, i.e. ‘cold’ colours.

What is an autonomous adenoma?

Most of the nodules on the thyroid gland are benign tissue growths, also known as adenomas. This benign, hormone-producing, hot thyroid nodule is usually caused by iodine deficiency. 

If the thyroid gland does not receive enough iodine, it releases hormones, that cause the thyroid cells to multiply. In addition, the pituitary gland (hypophysis) releases a hormone that stimulates the production of thyroid hormones (thyroid-stimulating hormone or TSH) and enlarges the thyroid cells, resulting in a benign thyroid tumour that produces uncontrolled levels of thyroid hormones (also known as an autonomous adenoma).

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