The thyroid is a soft, butterfly shaped gland that lies in the lower central neck, wrapped around the windpipe below the Adam's apple. Its primary function is the secretion of two hormones Thyroxine and Tri-Iodothyronine (commonly referred to as T4 and T3 respectively). T4 is released into the circulation by the thyroid and is converted to its active form T3 in the liver and kidneys. Thyroid hormones are essential for the normal development and function of many organ systems by carefully regulating cell metabolism, the chemical processes that occur at the cellular level. A simple analogy is that it provides the gasoline to ensure that our biological engine is running at just the right speed.

The release of the thyroid hormones is strictly regulated by a feedback mechanism between the thyroid gland and a small gland at the base of the brain called the pituitary through another hormone called Thyroid Stimulating Hormone (TSH). The body is in equilibrium if the blood levels of T4, T3 and TSH are all within the normal range, and these three blood analyses form the components of what is commonly termed a "thyroid function test".

Problems of the thyroid can broadly be classified into two groups:

          Problems of HORMONE PRODUCTION
          Problems of NODULAR DISEASE (nodules or lumps within the thyroid)

Problems Of Hormone Production

Problems of hormone production relate to either too much or too little circulating thyroid hormone. An overactive thyroid gland secreting excess T4 results in a person feeling "revved up", and is termed hyperthyroidism.

Symptoms of hyperthyroidism include:

          Rapid pulse
          Fine hand tremor
          Weight loss despite an increase in appetite
          Excessive sweating
          Heat intolerance

Conversely an underactive thyroid gland that is unable to produce sufficient amounts of T4 results in a condition called hypothyroidism, where everything slows down.

Symptoms of hypothyroidism include:

          Lethargy and malaise
          Weight gain
          Cold intolerance

Problems of hormone production are usually treated medically.

Hyperthyroid patients are given medication to reduce the production of thyroxine as well as to decrease the effects of the circulating hormone on the organ systems. In situations where medical therapy fails to adequately treat the disease, radioiodine therapy or thyroid surgery may be considered as alternative treatments.

Hypothyroidism is treated quite easily by taking thyroid hormone supplements.

Problems Of Nodular Disease

A normal thyroid gland is neither visible to the eye nor can be felt by clinical examination. Any part of the thyroid gland that can be seen of felt represents enlargement of the gland, and needs to be further evaluated.

A goiter is a common descriptive term that refers to enlargement of the thyroid gland. The goiter can be either diffuse, where there is uniform general enlargement of the gland, or, more commonly, nodular where there may be single or multiple discreet nodules or lumps contained within it.

Solitary thyroid nodules are the most common presentation of nodular disease, and the most important in terms of its relationship with thyroid cancer.

The Thyroid Head & Neck Surgery Centre