THYROID DISORDERS RESOURCE CENTRE

The thyroid gland is a small endocrine (hormone producing) gland situated in the neck, just below the Adam's apple. It has 2 halves, and is shaped somewhat like a butterfly.  It is responsible for producing the thyroid hormone, a vital hormone for normal body function.  Problems arise when there is under or over production of thyroid hormones by the thyroid gland, or the gland itself may grow abnormally, developing benign lumps or sometimes cancer.

The hormones produced by the thyroid gland are Thyroxine (T4) and Triiodothyronine (T3).

These hormones are responsible for the following:
• Controlling Metabolism
• Controlling Growth and Development

REGULATION OF THE THYROID GLAND

The activity of the thyroid gland is tightly controlled by the normal functioning of the Hypothalmic-pituitary-thyroid axis.  This axis is a team of 3 glands working in concert to ensure normal thyroid gland functioning.  The hypothalamus is part of the brain, and it produces Thyrotropin Releasing Hormone (TRH), which stimulates the Pituitary gland (situated at the end of a stalk at the base of the brain) to produce the Thyroid Stimulating Hormone (TSH).  It is this TSH which stimulates the Thyroid gland to produce the thyroid hormones T3 and T4. 


The system works a little like a boiler and thermostat.  The thyroid gland functions like the boiler which fires up to increase the metabolic rate of the body, whilst the hypothalamus functions like the thermostat, that controls the “temperature” of the “boiler”. 

If thyroid hormone levels are too low, the thermostat senses this, and signals to the “boiler” (the thyroid gland) to produce more “heat” (thyroid hormone).

On the other hand, if thyroid hormone (“heat”) levels are sufficient, a negative feedback to the “thermostat” (the hypothalamus) causes it to produce less TRH.  Lower TRH levels filter down to cause less thyroid hormone production.

WHAT CAN GO WRONG?

If something goes wrong with your thyroid gland, the changes may be very subtle initially, and symptoms may go largely unnoticed.  Symptoms of hypothyroidism for instance, can easily be passed off as normal fatigue and lethargy.

Some Conditions of the Thyroid include:

(i) Hyperthyroidism (overactive thyroid gland)

(ii) Hypothyroidism (underactive thyroid gland)

(iii) Goitre (enlarged thyroid gland)

(iv) Thyroid cancer

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