The thyroid is a tiny gland with a big job. Located in the neck, it secretes hormones that are responsible for the body's energy supply and for ensuring that organ systems run properly. The thyroid plays such a vital function in our health, January has been designated "Thyroid Awareness Month," with the goal of educating people on the importance of thyroid health.

To help shed some light on this oft overlooked subject, Healthline spoke with Dr. Jeffrey Garber, a leading expert on thyroid disorders and president of the American Association of Clinical Endocrinologists. Dr. Garber's book, The Harvard Medical School Guide to Overcoming Thyroid Problems, breaks down a complex topic into digestible and easy-to-understand language and has become a must-read for those suffering from thyroid disorders.

In your book, you likened the thyroid gland to the engine of a car. Can you explain that analogy?

The car is run by an engine, which relies on fuel. In the similar way, the thyroid takes a basic component — in this case iodine that acts as a fuel — and turns it into thyroid hormone that influences how energy gets transmitted to the body's organs and extremities. So if you look at the thyroid as the center for generating energy, that's where the analogy is. It's where the fuel goes in, combusts, and provides the power for everything else to work. When you gun an engine with the gears disengaged, it's similar to hyperthyroidism. There is lots of energy, but it's not effective. In hypothyroidism, the engine doesn't start, or it sputters.

The thyroid is responsible for a lot of different things. What is its most important function?

The problem you get into when you say "most important" is that we are all built differently. If people don't have thyroid hormone, several things happen. They'll get cold, everything slows down, they'll be a sitting duck for infection, organ systems won't work normally. So it's a question of which organ system is most vulnerable. If the electricity went out in your house, what would cause the biggest disaster? It would probably be different for every house.

So thyroid disorders can compound existing problems?

That's one possibility, but it could suppress other problems. When systems fail, the symptoms affect people in different ways. If people are more prone to depression, those are the people who are more likely to get depressed when their thyroid is low. But people who tend to be more hyper and always on the go might experience a slightly calming effect if their thyroid is low. Some people are more prone to constipation, so that might be the most prevalent symptom. On the other hand, if people have generally fast bowels, they may welcome a slowdown in that area. Everyone is wired differently. The thyroid, itself, is more predictable. When thyroid is low, your heart slows down. When it's high, your heart speeds up, but that doesn't mean your brain reacts in a predictable way. It's both fascinating and hard to pigeon hole.

It sounds like the symptoms of thyroid disorders are nonspecific and could be symptoms of other conditions. Seems like that would make for a tricky diagnosis.

That's exactly right. The symptoms aren't diagnostic, but they can be telling. When we hear symptoms, a hypothesis is generated. The person is a bit fatigued, they've gotten constipated, maybe they're a little cold, and there is no obvious reason for these symptoms that have been going on for a couple of weeks. So we check the thyroid, and it's off. Well, that person is a pretty good candidate, especially if those symptoms are new. And we'll administer treatment to see if it helps. On the other hand, if the thyroid tests come back normal, maybe the person has been experience some of these symptoms for years, it could just be how they're wired, and there is no thyroid problem. You have to know who the person is, their history, what's new, and what has changed. Most people are not preoccupied with every symptom they have. So a lot of time we get reticent people who say they haven't really noticed that much. But after you treat them, they realize there were other things going on.

So there aren't really any red flags?

Well, the more symptoms you have, the more likely that there is a problem. You used the right word earlier — "nonspecific." There is no single specific symptom or even physical finding, for that matter. An enlarged thyroid can be an overactive one or an underactive one — or it could function normally. A normal-sized thyroid can be all of those things, too.

After the diagnosis is made, what happens next?

It depends on the diagnosis. There are two sets of thyroid disorders. There are structural abnormalities, where the thyroid is too big or it has a lump in it. And there are functional abnormalities, where it is making too much or too little thyroid hormone.

Let's look at the structure first. If the gland is big and is causing symptoms — trouble swallowing, pain, breathing problems — that is all from the anatomy of it, the location and size. If there is a lump, is it benign or malignant? What happens next is predicated on the assessment of those situations. If you have a moderately enlarged thyroid with no lumps that functions normally, we might keep an eye on it and do nothing. If you have a growing thyroid that is causing symptoms, even if it's benign we may want to remove it. If it's growing and there is a suspicious lump, we'll take a biopsy and then treat it.

Functional abnormalities can be divorced from or related to structure. If the thyroid is producing too much hormone, it's imperative to reverse the excess. If there is too little thyroid, the goal is to restore it. The tricky part is when it is marginal, and that becomes a clinical judgment. If you are a chronically depressed person or infertile and trying to get pregnant, and your thyroid is off and contributing to the problem, I don't think therapy should be withheld. On the other hand, if you're a healthy 20-year-old who just ran a marathon and your thyroid tests are marginally off, I don't think you need to rush into therapy.

Let's assume the tests clearly show an overactive thyroid.

There are several ways to treat hyperthyroidism. One is to use medications to slow down the thyroid. Another is to remove the thyroid completely through surgery. And a third option is to damage or destroy it with radioactive iodine. And sometimes a combination of those is used. If the thyroid is marginally off, the fourth option is to just monitor it and see which way it goes. It could fix itself. But in any case, it's important to determine the origin of the problem. If the thyroid is inflamed and leaking hormone, it may fix itself. So basically the strategy is to determine if it's causing symptoms, if the person is susceptible to the excess hormone even if it's marginal, and what is the basis for the problem. Is there a chance of it fixing itself or is there no chance? So you streamline the therapy based on those criteria.

Now let's assume an underactive thyroid.

With an underactive thyroid, some of those cases will end up fixing themselves too — more so than we used to think 25 years ago. Some people — especially younger people — have transiently underactive thyroids. For example, if you have an inflamed thyroid, as it recovers it becomes underactive three-quarters of the time. So we need a sense of permanence before we say how someone should best be treated.

So outside of maybe cancer—it seems most types of thyroid disorders are treatable. Is the outlook for most of these positive?

Absolutely. All of it is treatable. And the good news about the cancers—if you can say that—is that most of the thyroid cancer we see is essentially curable, almost 90% of it. Now the problem is that that are a lot of people who don't feel well and happen to have thyroid disorders, so they don't often feel that the treatment is working. But the counter to that is there are limitations to certain therapies because there is more than one thing going on. But thyroid disorders, per se, are imminently treatable. That's not to say that every minor abnormality needs to be treated; it can be observed. But the resounding message is that while a thyroid disorder may affect your health, there is a great deal we can do about it.

Heredity plays a big role in determining thyroid risk. However, in the past it had a lot to do with iodine deficiency. Is that still a problem in the United States?

Well, it was certainly prevalent in the past. Back in the 1920s, as World War I soldiers were getting physicals, doctors noticed an iodine-deficiency in what we now call The Goiter Belt, a group land-locked states that shared similarities with high-altitude, under-developed parts of the world that experienced the same problem. Those states had an iodine-deficient diet because they weren't eating a lot of seafood and weren't near the ocean. So Morton's started iodizing its salt, and we essentially eliminated iodine-deficiency. We actually went the other way because in the 1970s iodine was used as a stabilizer in designer breads, and suddenly there was too much iodine in our diet. Then the iodine was taken out of the bread, and we began to move back to the center, and even back to a marginal deficiency, which is more of a problem during pregnancy and breastfeeding, when iodine intake requirements are higher. So one thing we try to get across to pregnant women is that their prenatal vitamins should have iodine. And curiously, many of those vitamins don't.

Are there any preventative measures that people can take when it comes to the health of their thyroid?

Knowing your family history is important. Being attuned to the symptoms and, if you are having them, bringing them up during routine exams is also important. My personal view is that if your doctor isn't coming up with an answer and you aren't feeling well for two or three weeks, think thyroid. Our book makes the point that you have to be an advocate of your own health. Be familiar with the thyroid and realize that it can affect a lot of different things. It may not affect you, but if your doctor isn't coming up with answers, think thyroid, especially if there is a family history. In this day and age, people have taken it upon themselves—for good reason—to be aware of a lot of different health symptoms. Thyroid is no different.

Are there any groups with a higher risk that should be more attuned than others?

Women, especially if there was a recent pregnancy. People over 60. Caucasian. Family history. People who come from a country with an iodine-deficient diet. People who have been exposed to radiation or are taking medications with a high level of iodine. Smokers also seem to have a higher risk. But thyroid disorders are most common in women over the age of 60.