What is the thyroid gland?

The thyroid gland is one of the largest hormone producing glands found in the body. It is located in the mid point of the neck, and has two lobes. The thyroid produces hormones which control how quickly the body uses energy and controls how sensitive the body can be to other hormones. It is controlled by the hypothalamus and the pituitary, and exerts an effect over every cell in the body.

Common thyroid problems include:

• Hypothyroidism (underactive thyroid)
• Hyperthyroidism (overactive thyroid)
• Goitre
• Thyroid nodule (lump within the thyroid gland)

Hypothyroidism

This condition occurs when the thyroid gland is not producing sufficient thyroid hormone. It is much more common in women than men, and is thought to be very much an under diagnosed condition; in other words, there are a lot of men and women who have a hypothyroid condition and are unaware of it. Hypothyroidism can be as a result of inflammation of the thyroid glands caused by the patient’s own immune system, whereby enough of the hormone-producing cells have been damaged to cause the production of the hormone to be reduced. The commonest form of this is called Hashimotos thyroiditis.

Hypothyroidism can also be brought about by medication used to treat an overactive thyroid gland, or surgery preformed to remove some of the thyroid gland in cases of thyroid cancer or a greatly enlarged thyroid gland (see goitre).

Symptoms of hypothyroidism include:

• Fatigue
• Weakness
• Weight gain or increased difficulty losing weight
• Coarse dry hair
• Dry rough pale skin
• Hair loss
• Cold intolerance
• Muscle cramps and frequent muscle aches
• Constipation
• Depression
• Irritability
• Memory loss
• Abnormal menstrual cycles
• Decreased libido

Hypothyroidism is easily diagnosed with a simple blood test. This test measures the level of Thyroid stimulating hormone (TSH) and levels greater than 5 mmol/litre are considered to be abnormal. It is also easily treated in most cases with medication taken on a daily basis. This medicine is a synthetic thyroid supplement.

Hyperthyroidism

This condition is characterised by excessive production of thyroid hormone. There are many different causes, the commonest being Grave’s Disease, which is an enlargement of the gland in conjunction with too much thyroid production. It is much more commonly seen in women then men, and is rarely seen in women over the age of 50.

Common symptoms include:

• Palpitations
• Heat intolerance
• Nervousness
• Insomnia
• Breathlessness
• Increased bowel movements
• Light or absent menstrual periods
• Fatigue
• Fast heart rate
• Trembling hands
• Weight loss
• Muscle weakness
• Warm moist skin
• Hair loss
• Staring gaze

Hyperthyroidism is diagnosed by firstly clinical history and examination, then by a blood test. An ultrasound scan of the thyroid gland is sometimes needed to locate any specific lumps which may be responsible for the hormone production.

Treatments include medication, surgery or radio-active iodine, depending on the underlying cause of the hyperthyroidism. A common side effect of treatment for hyperthyroidism is unfortunately an underactive thyroid gland after treatment has finished.

Goitre

This word describes an enlargement of the thyroid gland without the over or under production of thyroid hormone. It presents as a generalised thickening of the neck, or a more obvious lump on the gland. If unnoticed, goitres can grow to a significant size, and can cause symptoms such as difficulty breathing, difficulty in swallowing, cough or slight change in voice.

In larger goitres, surgery to remove them is the preferred choice. In small to medium sized goitres, a course of treatment with thyroid hormone will cause a shrinking in the size of the goitre.