Think of three things that can make or break your day. Your emotions, your appearance and your health are probably top of the list.

That's why it's important to be aware of a small gland at the base of your neck called the thyroid. Working properly, the thyroid can make you feel better, look better and keep you healthy. Here's what you should know about this vital gland:

Why does it matter?
Dr. Faye Goldman, a family physician in Ottawa, says the thyroid produces a hormone needed for metabolism. Since metabolism is the body's way of producing energy and building cells, thyroid function is essential to the entire body.

Left untreated, thyroid disorders can have serious, even deadly, outcomes. "It can affect the heart and the lungs," Goldman says. "In severe cases you can go into a coma from the lack of thyroid."

What goes wrong?
While there are many variations, the simple answer is your thyroid can under work – called "hypothyroidism" , or over work – known as "hyperthyroidism".

Goldman says the cause can be local, with the gland itself producing too much or too little thyroid hormone.

It's also possible to have a break down in the "feedback loop" connecting the thyroid and the brain. The pituitary, a hormone-producing gland in the brain, sends thyroid stimulating hormone (TSH) to the thyroid to tell it how much or how little thyroid hormone to produce. "In rare cases the pituitary can produce too much TSH," says Goldman. "It gets out of that communication loop and the TSH keeps (over)stimulating the thyroid."

How can you tell?
Hyper and hypothyroidism have one thing in common – both affect your metabolism. Beyond that the symptoms are completely opposite.

Hyperthyroidism
With an overactive thyroid, your metabolism shifts to overdrive. You may feel anxious, have a quick heart rate, and experience tremors in your hands. Bowel movements may be looser and increase in frequency. You may lose weight without changing your diet; sometimes to the point of ill-health.

Hypothyroidism
Your metabolism hits rock-bottom. You can feel exhausted; even depressed. Your heart rate may slow. Often hair and skin dry out and facial expressions become dull. You can experience constipation along with fluid retention, puffiness and swelling. While you may gain weight, don't blame your thyroid for twenty or thirty extra pounds. Rather it's that five or ten you just can't get rid of that's likely caused by hypothyroidism.

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Thyroid disorders are common and can happen to anyone. However, Goldman says certain people are at increased risk including:

• Those with a family history. In particular, a condition called Hashimoto's thyroiditis tends to run in families;
• Anyone who's had treatment (such as radiation) affecting the neck or thyroid. If the thyroid is damaged it can stop working, resulting in hypothyroidism;
• New moms, who are at risk for post-partum thyroiditis – a condition in which the thyroid malfunctions following pregnancy.

Goldman says doctors generally don't test for thyroid conditions as a matter of course. That's why it's important for patients – especially those falling into the higher-risk categories – to be aware of the symptoms associated with thyroid problems. "At an annual check-up you can ask questions to see if there's an issue," Goldman says. "During and after pregnancy, and in people with strong family histories of thyroid disorders, I would certainly ask questions more often and my threshold for testing would be lower."

The good news
While the symptoms of thyroid conditions are unpleasant and, untreated, the long-term effects can be dangerous, there is good news.

Easy diagnosis
All that's needed to check your thyroid is a trip to the lab for a simple blood test.

Straightforward treatment
The usual treatment for hypothyroidism is to take one pill once a day. "Generally there are no side effects," says Goldman. "You're replacing the hormone your thyroid gland should be producing and taking it by mouth." The treatments for hyperthyroidism vary a bit more but are well-established and mostly low-risk.

The best news of all? As unexpectedly as it malfunctioned, your thyroid could start working properly again. Most cases of hypothyroidism are considered chronic – something you'll have for the rest of your life – but it's not unusual for post-partum thyroiditis to disappear once the hormonal upheaveal of child-bearing has passed. And for those experiencing hyperthyroidism, Goldman says there's good reason to be optimistic. "There's always the chance, a good chance, it'll revert to normal."

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