5 things you should know about thyroid function

Shaped like a butterfly and nestled just below the larynx (Adam's apple), the thyroid gland is a key player in the body's metabolism. Disturbances in thyroid function can occur at any age, but they most commonly occur after the age of 40.

Since it can take many years before symptoms of either hypo- (underactive) or hyper- (overactive) thyroidism appear, here's what women (they develop thyroid disorders at a rate of almost eight times that of men) should know about thyroid dysfunction.

1. A genetic condition called Hashimoto's thyroiditis is the most common cause of hypothyroidism.
This thyroid disorder occurs when the body produces antibodies against itself. These antibodies prime the thyroid gland to see itself as "foreign," setting up a state of chronic inflammation, which interferes with the secretion of T4 (also known as thyroxine) and T3 (triiodothyronine), hormones that help regulate the body's metabolic rate. When your T3 and thyroxine levels are low, you may gain weight, feel lethargic and experience difficulties with memory.

2. An overactive thyroid can be mistaken for an emotional disorder.
Symptoms of hyperthyroidism can include anxiety, mood swings, irritability and depression. There are two main causes of hyperthyroidism:

• Graves' disease. As with Hashimoto's thyroiditis, Graves' disease is a genetic disorder in which the body produces an antibody against itself, but in this case, the antibody prompts the gland to overproduce rather than underproduce thyroid hormone, explains Dr. Jerald Bain, an endocrinologist at Mount Sinai Hospital in Toronto.

• Subacute thyroiditis. Probably caused by a virus, this low-grade condition causes inflammation in the thyroid gland, which triggers the release of thyroid hormone. "This form of hyperthyroidism has a limited life span," notes Bain, "and it may or may not be symptomatic."

3. Treatment for thyroid disorders depends on whether you want to produce more or less thyroid hormone.
If you have hypothyroidism, thyroxine replacement therapy will help balance hormone levels. But whether to take synthetic thyroid hormone, which is most like the human hormone and which most doctors prescribe, or to opt for what's called "natural" (or "dessicated") thyroxine, which comes from cows, is up for debate.

To treat an overactive condition such as Graves' disease, doctors usually opt for antithyroid drugs such as propylthiouracil or methimazole (Tapazole), but if these don't work, radioactive iodine is another option. Radioactive iodine is taken up by the thyroid gland, reducing its function, thereby limiting hormone production. Doctors treat subacute thyroiditis with an anti-inflammatory agent, but because inflammation can damage the gland, they typically add thyroxine therapy while the gland repairs itself.

(Click here for more helpful information on thyroid health.)

Page 1 of 2