Enlargement of the thyroid gland (goitre)

The Latin term ‘struma’ translates as ‘swelling of the throat’, ‘throat tumour’ or just ‘thick throat’. In medicine, a struma (or ‘goitre’) is the term used to describe an enlarged thyroid gland. With this disorder, the entire thyroid gland may be larger than normal, or one or more nodules may have formed on the thyroid gland. Goitres are often caused by an iodine deficiency.

What is a thyroid enlargement?

When nodules or growths form on the thyroid, this is usually a sign that it is trying to compensate for an iodine deficiency. Without this ‘trace element’, the thyroid gland is not able to produce its vital hormones.

Around a third of the population will experience an enlargement of the thyroid gland in the form of a goitre or struma, with women being around four to five times more likely to be affected than men. In the past, goitres were very common due to the lack of iodine in our diet. In recent years, successful attempts have been made to improve our overall iodine intake, and nowadays it is very rare for goitres to be diagnosed in newborns, and children of school age also tend to have very healthy thyroid glands.

Symptoms

Small goitres often go unnoticed by the affected individual because they do not cause pain, are not visible or palpable, and do not restrict the individual in any way.

However, if goitres grow, they can lead to local symptoms such as a feeling of pressure or tightness in the neck area or forced clearing of the throat. Some patients experience a constant sensation of having a ‘lump in the throat’, while others may only notice the growth of their thyroid gland due to a change in their collar size when buying clothes.

If the enlarged thyroid gland is also pressing against the oesophagus, the individual may experience problems with swallowing. If the thyroid gland is compressing the trachea, this can cause breathing difficulties, and the individual may notice that they are breathing more loudly than usual. As a result, those affected may begin to suffer from shortness of breath during exertion or when moving their head a certain way.

If the goitre is growing behind the sternum, this can affect the individual’s breathing and their cardiovascular system. In addition, if the goitre is very large, it can press against the nerves of the vocal cords, the oesophagus or even the blood vessels, causing hoarseness, difficulty swallowing or even vascular congestion in the head.

Causes

Goitres can be caused by a variety of different factors, but are most commonly caused by iodine deficiency. Because iodine is an elementary component of the thyroid hormone, an iodine deficiency leads to a deficiency of effective thyroid hormone in the body. As a result, the thyroid cells multiply and the pituitary gland (hypophysis) releases more of the thyroid-stimulating hormone TSH to stimulate the production of thyroid hormones T3 and T4. This in turn causes the thyroid cells to enlarge. In addition, new blood vessels and new connective tissue are formed. In this way, the thyroid gland tries to compensate for the iodine deficiency and to utilise the available iodine as effectively as possible. At the same time, however, the thyroid gland grows in size and a goitre forms.

Other causes of a goitre may include:

  • hormone changes during puberty, pregnancy or menopause
  • inflammation of the thyroid gland (known medically as thyroiditis), for example due to bacterial or viral infections
  • a condition known as thyroid autonomy, whereby the thyroid gland produces uncontrolled levels of hormones
  • a rare condition known as acromegaly, which causes pronounced enlargement of the extremities and protruding body parts such as the nose, ears and chin
  • a malignant tumour in the thyroid gland (thyroid cancer)
  • the formation of metastases (secondary tumours) of other malignant tumours in the thyroid gland
  • underactive thyroid gland
  • Graves’ disease
  • certain medications such as thyrostatic drugs, which are used to treat hyperthyroidism, or antidepressants with lithium as an active ingredient
  • altered thyroid enzymes
  • ineffective thyroid hormones, i.e. hormone resistance (rare)
  • cysts in the thyroid gland
  • bleeding after injury to the thyroid gland

Diagnosis

Goitres are often discovered by chance during a routine examination, as patients rarely go to see a doctor with a goitre that is gradually getting bigger. Anyone who discovers a change in the area of the thyroid gland should always consult a doctor. The doctor will be able to rule out serious illnesses using appropriate examination methods, or will refer you for professional treatment and help you to manage symptoms such as difficulty swallowing or breathing problems.

If you think you may have a goitre, it is important to consult a specialist in hormonal diseases, known as an endocrinologist. They will start by establishing whether the patient is eating enough iodine-containing foods, and will check their hormone levels. They will also perform various examinations, including a sonography (ultrasound). This allows the doctor to visualise the position, shape and size of the gland and to observe the tissue structure of the thyroid gland. This also allows them to detect cysts on the gland, as these appear brighter in ultrasound, whereas nodules appear darker.

If the ultrasound examination indicates the presence of nodules, the patient will be referred for a nuclear medical examination (scintigraphy) and, if necessary, a tissue sample will be taken from the thyroid gland using a fine needle (fine-needle biopsy or FNB) to rule out the possibility of the nodule(s) being a malignant thyroid carcinoma.

Treatment

If the patient is diagnosed with a goitre caused by iodine deficiency, there are three main treatment options available:

If the goitre has already existed for an extended period of time, it can often no longer be treated with medication, which is why the doctor will normally recommend surgery. As a rule, only part of the thyroid gland is removed so that, in the best case scenario, there is a sufficiently large and functioning part of the gland left to produce the vital thyroid hormones, sparing the patient the need for life-long hormone replacement therapy. However, if the thyroid gland has to be removed completely, the patient will need to take thyroid hormones in tablet form for the rest of their life.

Nuclear medicine treatment with radioiodine therapy is used if the goitre keeps returning after treatment with conventional medicines, or if there is an increased risk of the patient needing surgery. In the course of radioiodine therapy, the patient is given a radioactive iodine isotope. This accumulates in the thyroid gland, partially damaging the tissue and thus reducing the volume of the gland by up to 50%.

Aftercare

If you have been diagnosed with a goitre, there are various things you should be doing to improve your condition (although these rules also apply to people who have not been diagnosed with a goitre):

  • Have regular medical examinations (this especially applies to older people) in order to detect a goitre as early as possible and have it professionally treated.
  • Always keep an eye on iodine requirements, especially during pregnancy.
  • In general, make sure you eat a diet rich in iodine or use iodised table salt.

The amount of thyroid tissue removed during surgery affects the hormonal balance of the body. The greater the amount of thyroid tissue that is removed, the greater the drop in hormone levels. Conversely, removing only a small amount of tissue results in a lower hormonal change, but the risk of the thyroid enlargement reoccurring is far greater.

The objectives of aftercare in the course of thyroid surgery therefore comprise optimal (medicinal) control of the thyroid hormones, combined with the best possible prevention of relapse (recurrent prophylaxis). The choice of medication administered mainly depends on the size of the remaining thyroid gland. If the thyroid gland had to be completely surgically removed, the patient will require life-long hormone replacement therapy with thyroxine.

FAQs

Why is iodine so important for preventing thyroid enlargement?

The thyroid gland requires iodine to produce the hormones T3 and T4. It is therefore important to ensure a regular iodine intake as part of your diet. The daily requirement for an adult is 180 to 200 micrograms. People who predominantly eat products that are low in iodine should compensate for any deficiency by using iodised table salt.

Are there different size categories for goitres?

The World Health Organization ( WHO) uses the following grading system for goitres:

  • Grade 0: The goitre can only be detected via ultrasound
  • Grade 1: The enlargement of the thyroid gland is palpable, but not visible
  • Grade 1a: The enlargement of the thyroid gland is palpable, but not visible even when the head is tilted backwards
  • Grade 1b: The enlargement of the thyroid gland is palpable and becomes visible when the head is tilted backwards
  • Grade 2: The enlargement is palpable and is visible even with the head in a normal position
  • Grade 3: Very pronounced goitre causing local discomfort such as impaired breathing

What are the classification criteria for a goitre?

Goitres are not only classified according to their size, but also based on other criteria:

  • Anatomical position: Goitres develop either in the neck area (eutopic goitre), at the base of the tongue or behind the sternum and into the trachea (dystopic goitre).
  • Composition: An important distinction is made between a uniformly enlarged thyroid gland made up of homogeneous, i.e. identical, tissue (struma diffusa) and a thyroid gland with one or more nodules (struma nodosa). Sometimes, these nodules produce thyroid hormones, in which case they are called hot nodules. In contrast, cold nodules do not produce thyroid hormones.
  • Function: The medical world distinguishes between three functions in relation to goitres: The ‘euthyroid goitre’ produces just as many thyroid hormones as a healthy, non-enlarged thyroid. With a hyperthyroid goitre, the blood contains too high a concentration of the hormones T3 and T4. In contrast, with a hypothyroid goitre the concentration is too low. This means that the level of hormone production cannot generally indicate the size of the thyroid gland.

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