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Thyroid

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The Health Index

The thyroid is a butterfly-shaped gland located in the neck. Its purpose is to make thyroid hormones, and it is virtually the body’s internal motor, setting the speed at which the body works. Thyroid hormones affect most cells in the human body by regulating the basal metabolic rate as well as heat production. This is why people with underactive thyroid glands often struggle to lose weight, feel the cold, and have low energy – imagine a record player playing a record at a reduced speed.

Image by Deb Kennedy

The most common thyroid condition is hypothyroid – a condition in which the thyroid is under-functioning. It is more common in women than in men.  One hypothyroid condition – Hashimoto’s hypothyroid – is an autoimmune condition. Hyperthyroidism is a condition in which the thyroid is overactive, and there is too much thyroid hormone.

 

Unlike hypothyroidism, hyperthyroidism has an over-stimulating effect. Sometimes patients experience both hypothyroid as well as hyperthyroid symptoms. In Hashimoto’s, patients can fluctuate between the two.

What are the causes of thyroid disease?

The cause of hypothyroidism may be a disorder of the thyroid gland itself. Hypothyroidism is seldom congenital. It is usually the result of later loss or destruction of intact thyroid tissue, for example through an overactive immune system. Hypothyroidism can also occur if the regulatory centres in the brain that are important for hormone production, the hypothalamus and the pituitary gland, do not work properly. A severe iodine deficiency in the diet can also lead to hypofunction in rare cases - usually combined with an enlargement of the thyroid gland (goitre).

 

A hypofunction can be congenital, which is the case in about 1 in 4000 new-borns. For the development and survival of the baby it is crucial that the thyroid is checked at birth. In adulthood, chronic thyroiditis is the most common cause of the development of hypothyroidism. This is usually caused by an autoimmune disease called Hashimoto's thyroiditis. If the thyroid gland is overactive (hyperthyhroid) or the patient has a goitre, the medical treatments to combat this can also unintentionally cause hypothyroidism.

 

These treatments include:

  • Excessive doses of drugs that inhibit the production of thyroid hormones (thyrostatic drugs)

  • Radioiodine therapy

  • Removal of the thyroid gland or parts thereof

  • X-ray of the anterior neck region in cancer

Although the causes for hyperthyroidism are varied, more than 95% of hyperthyroidism is caused by Graves' disease or by a thyroid autonomy. Like Hashimoto’s thyreoditis, this is an autoimmune disease. For reasons as yet unknown, various antibodies are produced against the thyroid gland.

 

The most important of these (TSH receptor autoantibodies, "TRAK") stimulate the hormone-producing cells, resulting in increased production of thyroid hormones. As this production is no longer adjusted to the body's actual needs, this leads to hyperthyroidism. Hyperthyroidism is usually also associated with an enlargement of the thyroid gland (goitre). Typical of Graves' disease is that the autoimmune condition not only affects the thyroid gland, but also the tissue of the eye sockets (endocrine orbitopathy) and the skin of the lower leg (pretibial myxoedema).

Functional autonomy means that parts of the thyroid gland (individual nodes or “autonomous adenomas”), or all of the thyroid gland tissues, produce hormones on their own. The so-called autonomous areas are thus no longer subject to the control of the pituitary gland. This can lead to hyperactivity if hormone production exceeds the body's requirements. The cause of thyroid autonomy is often a prolonged enlargement of the thyroid gland due to iodine deficiency (iodine deficiency goitre).

 

As an accompanying symptom, nodules may or may not form. It is typical that autonomic nodules show up very actively during scintigraphy - an imaging procedure that can provide information about the activity of the thyroid gland tissue (so-called “hot nodules”).