Hyperthyroidism

Published on 02/03/2015 by admin

Filed under Basic Science

Last modified 02/03/2015

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Hyperthyroidism

Thyrotoxicosis occurs when tissues are exposed to high levels of the thyroid hormones. Used correctly, the term ‘hyperthyroidism’ refers to the over-activity of the thyroid gland, but thyrotoxicosis can also occur from ingestion of too much T4 or, rarely, from increased pituitary stimulation of the thyroid.

Causes

Hyperthyroidism can result from:

Graves’ disease is the most common cause of hyperthyroidism, and is an autoimmune disease in which antibodies to the TSH receptor on the surface of thyroid cells appear to mimic the action of the pituitary hormone. The normal regulatory controls on T4 synthesis and secretion are lacking. Pituitary secretion of TSH is completely inhibited by the high concentrations of thyroid hormones in the blood.

Although the eyelid retraction commonly seen in the patient with Graves’ disease (Fig 46.3

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