The thyroid gland is located in the neck, in front of the windpipe, and produces a hormone called thyroxine. Thyroxine is important in regulating metabolic rate and is essential for the proper functioning of all bodily organs. Thyroid disorders may be due to over- or under-production of thyroxine, or due to a growth (ie. a tumour) in the gland itself:
Hyperthyroidism or Thyrotoxicosis
Overproduction of thyroxine, due to a variety of causes:
Graves' disease: The thyroid produces excess thyroxine on its own.
Toxic adenomas: Excess secretion of thyroxine by a nodule in the thyroid gland. Sometimes, several
nodules may be present.
Subacute viral thyroiditis: Leakage of pre-formed thyroid hormone from viral infection of the thyroid,
resulting in temporary hyperthyroidism that generally lasts a few weeks but may persist for
Pituitary gland malfunction or cancerous growths in the thyroid gland
Hypothyroidism or Myxoedema
Underproduction of thyroxine due to one of these common causes:
Hashimoto's thyroiditis: The thyroid gland stops functioning due to abnormal regulation caused by the immune
Removal of the thyroid gland: The thyroid may have been surgically removed or chemically destroyed.
Medication-induced: Lithium, amiodarone, or certain contrast dyes given before some X-rays, may cause
shutdown of the thyroid gland.
Pituitary gland malfunction
Thyroid cancers frequently present as a lump or growth in the neck. They may not cause any symptoms, but may be noted to grow quite rapidly, causing compression of the windpipe (breathing difficulty) or foodpipe (swallowing difficulty).
Symptoms of hypothyroidism tend to develop slowly, often over the span of several years. At first, one might feel tired and sluggish. Later, other symptoms of a slowing down in metabolism may develop, including:
· weight gain, despite no increase in appetite
· poor healing of cuts and wounds
· increased sensitivity to cold
· muscle weakness
· joint or muscle pain
· pale dry skin
· horseness of the voice
· excessive menstrual bleeding
On the other hand, hyperthyroidism cause increased metabolic rate. Symptoms are opposite to that of hypothyroidism and often include:
· weight loss in spite of good appetite
· heat intolerance
· frequent loose stools
· more fidgety and quick-tempered
· muscle weakness
· poor effort tolerance
· reduced menstrual flow