Spotlighting Your Thyroid
In This Chapter
- How your thyroid regulates your cells
- Your metabolism and RMR
- Understanding thyroid hormones
- Common thyroid diseases
Thyroid disease has become a quiet epidemic. The American Association of Clinical Endocrinologists (AACE) estimates 1 in 10 Americans have thyroid disease. That’s over 30 million people—more than the number of Americans with diabetes. Women are over five times as likely to have thyroid disease as men. And the chances of having a thyroid disorder increase with time—17 percent if you’re a woman and 9 percent if you’re a man by the time you reach age 60.
The AACE also estimates that half of those with thyroid disease don’t know it. That’s because thyroid issues can be difficult to recognize, even by doctors. Many people suffer from thyroid problems for years before being accurately diagnosed. Further, even if you’re receiving treatment for thyroid disease, there’s a strong chance you’re being underserved, because many doctors rely too much on lab results and not enough on patient symptoms.
As alarming as the number of cases already is, the thyroid disease rate is expected to increase due to the thyroid’s special issues with environmental toxins. The good news is that almost all thyroid disease is thoroughly treatable. The challenge is to be fully informed so you’re empowered to recognize a problem and seek the right kind of help.
This chapter will take the mystery out of your thyroid. We’ll explain what your thyroid is, what it does, and how it can go wrong. Whether you only suspect you have thyroid disease or are certain of it, you’ll end up with the knowledge you need to start making informed choices and take appropriate next steps.
The Butterfly in Your Neck
Your thyroid is a butterfly-shaped gland that resides in your neck. It’s wrapped around your windpipe, just above your collarbone and below your Adam’s apple. Its name stems from the Greek word for “shield” (another metaphor for its shape).
Definition
The thyroid is a gland in your neck that behaves like your body’s thermostat, raising or lowering the amount of activity taking place based on your current needs. Your thyroid affects every part of your body by secreting hormones into your bloodstream. These hormones then charge up your cell’s internal power batteries, which are called mitochondria.
Your thyroid consists of left and right “wings,” called lobes, connected by a middle section called the isthmus. Your thyroid’s two lobes do the same job, each performing half of the necessary labor. They also effectively back each other up; if anything ever goes wrong with one lobe, the other can take over the entire workload.
The thyroid’s shape varies by gender. If you’re a man, it’s narrower and thicker; if you’re a woman, longer and flatter. That’s why the Adam’s apple tends to be visible in men only. Women have an Adam’s apple, too—it’s merely the cartilage between your thyroid and larynx—but the shape of the thyroid typically hides it from sight. (In fact, some ancient Greeks believed the purpose of the thyroid was to provide women with a pleasing neckline.)
Your thyroid isn’t very large; it’s roughly the width and thickness of four credit cards stacked on top of each other, and weighs 10-30 grams (0.35-1.06 ounces). Despite its relatively small size, though, your thyroid plays a critical role in your life.
The thyroid gland.
(Licensed from Shutterstock Images)
Your Energy Control Center
The thyroid has just one job, but it’s of immense importance: it makes hormones that regulate the energy level, growth, and reproduction of every cell of your body. That means your brain, heart, lungs, liver, skin, tissues, and all other body parts depend on your thyroid to stay “powered up” and active, and to remain healthy by generating new cells to replace old ones.
Thyroid Factoid
Your thyroid is one of the glands in your body’s endocrine system. That means it secretes a chemical, or hormone, directly into your bloodstream that regulates targeted areas of your body. The main difference between your thyroid and most other glands is that its target is every cell in your body.
More specifically, each of your cells contains “power plants” called mitochondria. Simple cells contain just one, while more complex cells can contain several thousand mitochondria. Mitochondria take glucose (a fundamental sugar your body creates from the food you eat) and convert it into energy called adenosine triphosphate, or ATP. The cell then uses the ATP to fuel its activities (such as repairing your body, moving your body, firing thoughts in your brain, or reproducing).
How much or how little glucose the mitochondria convert into ATP is determined by the thyroid hormones circulating in your bloodstream. These hormones have a similar effect to your foot on a car’s gas pedal, sending a message to either speed up or slow down. The mitochondria then function as little engines that convert your gasoline (glucose) into power (ATP) for driving your car (body).
The decisions about when to raise or lower cellular activity come from a portion of your brain called the hypothalamus. When your hypothalamus senses more energy is needed, it sends a chemical signal to an organ just above your sinuses that’s about the size of a pea. This organ is called the pituitary gland.
Your pituitary gland then responds by producing thyroid stimulating hormone, or TSH. As its name indicates, TSH stimulates your thyroid, effectively telling it “We need more power. Get to work and make more hormones.” Your thyroid then complies, making its hormones available to the mitochondria in each of your cells.
Definition
Thyroid stimulating hormone (TSH) is the chemical regulator of your thyroid. When your body needs more energy, your pituitary gland secretes TSH, which spurs your thyroid to produce hormones. TSH is also an important diagnostic tool, because measuring its levels in your blood helps a doctor determine whether your thyroid is making too little of its hormones (TSH will be high) or too much (TSH will be low).
You can think about this energy management system as a company. The hypothalamus is the president, making “big picture” decisions about when to increase or decrease energy production. The pituitary gland is the vice president who relays those decisions. The thyroid is the company manager, sending out or holding back encouragement for energy production to each of the workers. And the mitochondria are those workers—and their activity has a huge impact, because there are trillions of them.
The scenario is actually a little more complicated, because various areas of your body can choose precisely when to make use of the thyroid hormones. It’s as if your body was divided into different departments run by field-level managers, some of whom can decide whether the “speed up production” orders for the whole company are appropriate at that moment for that particular department. Overall, though, if your thyroid is churning out hormones, your cells will become more active.
Metabolism and Your Thyroid
The energy level set by your hypothalamus and enforced by your thyroid is called your metabolism. If you hear someone complaining that he’s overweight because “I have a slow metabolism,” he’s actually saying that his thyroid is underactive. If that’s truly the case, he should see a doctor (see Chapter 4). On the other hand, he may simply be eating too much and exercising too little (see Chapter 19).
As long as you’re alive, your metabolism will never be set to zero. Even when you’re doing nothing strenuous, your body needs to keep your heart beating, your lungs breathing, your brain processing information, and so on. A measure of this base level of activity is your resting metabolic rate, or RMR, which represents the minimum number of calories your body will burn up in 24 hours.
Thyroidian Tip
If you Google “resting metabolic rate,” you’ll find free online calculators that will approximate the number of calories your body burns in 24 hours based on such factors as your height, weight, age, and gender. For example, the RMR for a man is typically in the 1,600-2,000 calorie range, while the RMR for a woman is usually 1,200-1,400 calories.
Your RMR is responsible for burning up the vast majority of your calories—typically, 65-75 percent. And it’s RMR that your thyroid is primarily designed to regulate.
Of course, you have some control over your body’s energy management, too. When you choose to walk to work instead of drive, and to take the stairs instead of the elevator, you’re sending messages to your brain to burn up more calories. Your hypothalamus will notice your demands for higher production and set in motion the sequence of events that causes your cells to turn stored fat into glucose, and then ATP.
Exercise and other physical activity typically burn up only 15-25 percent of your calories. (The other 10 percent is used up dealing with food.) However, intense exercise can also raise your RMR for hours afterward, burning additional calories indirectly. Further, if you exercise regularly you’ll reduce fat and increase lean muscle, and that will raise your metabolism, and your RMR, to a perpetual new high. (To learn more, see Chapters 19 and 20.)
So while there’s a lot of energy regulation going on inside your body that you don’t directly control, you can opt for adjustments to your lifestyle to make this system accommodate your wants and needs … as long as your thyroid is healthy.
If your thyroid starts malfunctioning, however, it will typically throw off your RMR by a whopping 30-40 percent in either direction—roughly the equivalent of the number of calories you’d burn by running six miles a day. And a change in weight is only one of many problems you may experience, as we’ll discuss later in this chapter.
The Iodine Connection
Your thyroid makes its hormones by combining two ingredients that you consume every day (probably without even realizing it). The first is tyrosine, which is an amino acid that’s found in many high-protein foods such as milk, cheese, yogurt, soy, chicken, turkey, fish, pumpkin seeds, sesame seeds, and almonds. Unless you’re on a special low-protein diet, you’re likely to have plenty of tyrosine in your system.
The second is iodine. Your thyroid is unique in that it’s the only gland that absorbs iodine; the rest of your body ignores this chemical. You require only a tiny amount of iodine daily—generally 150-300 micrograms (mcg)—and whatever iodine you consume quickly gets sucked into your thyroid. If you eat fresh vegetables grown from iodine-rich soil or eat seafood, you probably take in all the iodine you need without even trying.
If you don’t eat much produce, though, or if you live far from a coastal area (and from iodine-rich oceans), you may have to devote some attention to iodine.
That’s especially so because iodine has become less ubiquitous. For example, it used to be the norm for fast-food restaurants and makers of processed foods to use iodized salt, which is a simple and inexpensive source of iodine (containing 45-80 mcg of iodine per gram of salt). But in part due to concerns about these salt-heavy food producers overdosing customers on iodine, most of these companies have switched to regular salt—which means a frozen dinner may provide you a great deal of sodium but zero iodine.
Similarly, in the past iodine was used in most baked goods as a dough conditioner. Now bromides often take its place, so there’s no way to know whether your bread and rolls contain iodine unless you ask your bakery.
Dairy products also used to be a major source, because dairy manufacturers used iodine as a sanitizer; but synthetic compounds are now sometimes employed instead, so you can’t consistently count on dairy foods as iodine sources.
If you have reason to suspect you’re lacking in iodine, there are still many cheap and readily available sources. They include vegetables grown in iodine-rich soil, iodized salt, sea salt, and multivitamins that include 50-100 mcg of iodine. You can also eat seafood, including seaweed, which has lots of natural iodine. Inexpensive and low-calorie options include the seaweeds nori, wakame, and dulse (see Chapter 3).
Thyroid Factoid
While iodine is plentiful in most industrialized countries, it isn’t everywhere. Hundreds of millions of people live in areas with iodine-deficient soil, and worldwide this is the top cause of thyroid-related ills—including such tragic birth defects as cretinism. Happily, this situation is improving. The World Health Organization has worked to reduce iodine deficiency from impacting 30 percent of the world’s population in 1990 to less than 15 percent today.
While too little iodine will create thyroid issues, too much iodine isn’t good either. You should consume no more than 1,000 mcg daily, and preferably stay within the 150-300 mcg range.
The “T” Factor
Assuming you have enough tyrosine and iodine in your system, your thyroid makes its hormones in two basic steps. First, it induces a chemical process that converts tyrosine into thyroglobulin, which is a protein specifically designed to bind with iodine. Your thyroid then combines a thyroglobulin molecule with 1 to 4 iodine atoms. The number of atoms attached determines the type of thyroid hormone that results.
If your thyroid attaches four iodine atoms, the hormone thyroxine (also called tetra-iodothyronine) is produced. It’s most commonly referred to as T4 because it’s made from a thyroglobulin molecule (T) combined with four iodine atoms (4). T4 comprises 80-90 percent of the hormones made by your thyroid.
T4 is a “storage” hormone. Instead of performing actions on your body, it’s designed to circulate in your bloodstream, and be stored in your tissues, until thyroid hormones are needed by a particular area of your body.
When energy is called for, an enzyme named deiodinase type 1 is used to strip off a single iodine atom from the outer ring of T4 molecules. Deiodinase type 1 is stored in your liver, kidneys, brain, pituitary gland, muscles, skin, and tissues, making it rapidly available to every area of your body.
Converting T4 to a thyroid hormone with three iodine atoms results in tri-iodothyronine, or T3. And it’s T3 that actually does the work of powering up the mitochondria in your cells.
Definition
T4 and T3 are the most important of the four hormones produced by your thyroid. T4 is a storage hormone that circulates in your bloodstream, or resides in your tissues, until some area of your body needs energy. The T4 is then converted into T3; and the T3 enters cells and “recharges” them by powering up their mitochondria.
It may seem wasteful to create T4 just so it can be transformed into T3. But T4 remains potent for about eight days in your bloodstream and tissues, while T3 retains its power for only around 10 hours. T4 therefore gives each region of your body the flexibility of having a thyroid hormone constantly available, and then “activating” it via conversion to T3 whenever a quick energy boost is needed.
In addition to T3 being created via T4 conversion, your thyroid makes T3 directly, although in much smaller quantities than T4. Your thyroid’s T4-to-T3 production ratio is roughly 10:1. (Put another way, around 10 percent of the hormones your thyroid produces are T3.)
No one is certain why your thyroid creates T3 along with T4; but it’s become a source of heated controversy. If your thyroid is underperforming, most doctors will prescribe Synthroid, which is a synthetic version of T4. The theory is that since your body can convert T4 to T3, Synthroid’s T4 is all you need. However, many thyroid experts argue that your thyroid must be producing both T4 and T3 for a good reason, and that your medication should therefore also be a mix of T4 and T3. That’s backed up by real-world experience; as many as 1 out of 3 patients don’t do well with T4 medication alone. As a result, an increasing number of doctors are prescribing a combination of Synthroid and Cytomel (which is synthetic T3); or desiccated thyroid such as Nature-Throid (which is a natural mix of T4 and T3 derived from the thyroid of pigs). To learn more and decide which option is best for you, see Chapters 3 and 8.
Thyroidian Tip
The enzyme deiodinase type 1 is made in part from the chemical selenium. If you happen to be low on selenium (which can be detected via blood tests), then your body won’t be able to convert enough T4 to T3. The simplest solution is to eat a single Brazil nut daily, which provides around 80 mcg of selenium. You’ll receive the rest of the 200 mcg of selenium you need without even trying from eating other nuts, whole grains, and/or seafood. Don’t regularly eat more than one Brazil nut a day, though, or you’ll end up overdosing. (You can also buy selenium in 200 mcg pill form, but consuming it via food is actually more effective … and more fun.)
While T4 and T3 comprise the vast majority of hormones your thyroid produces, they’re not the whole story. Roughly 4 percent of these hormones are T2 and T1. As you’ve probably guessed by now, T2, or do-iodothyronine, is made with two iodine atoms. Until recently, most doctors considered T2 to be useless. Some researchers didn’t believe your thyroid would create something for no reason, however, so they took a closer look; and now preliminary studies indicate T2 plays a role in metabolism and burning fat. It may also help with T4-to-T3 conversion. Mono-iodothyronine, or T1, still has no known purpose so far. However, researchers are taking a close look at it, too.
T2 and T1 are especially relevant when considering treatment. The only prescription medication that includes all four types of thyroid hormone is desiccated thyroid. That means if your thyroid has entirely stopped working, or if your thyroid has been removed, desiccated thyroid is your only option for continuing to have a normal amount of T2 and T1 in your body. Your doctor may give you a hard time if you request desiccated thyroid, but the reasons she provides are likely to be historical ones that have been obsolete for decades; to learn more, see Chapter 3.
One other thyroid hormone you may hear about is reverse T3. This is created when a batch of T4 is no longer needed (e.g., after it has outlived its “expiration date” of potency, or when your bloodstream has too much T4). Just as your body creates T3 by stripping off an iodine atom from the outer ring of T4 molecules, it creates reverse T3 by stripping off an iodine atom from the inner ring of T4 molecules. The reverse T3 will then be flushed out of your body.
Crash Glanding
Some alternative medicine practitioners claim reverse T3 has special significance in diagnosing disease (see Chapter 3). However, to date the evidence doesn’t support reverse T3 being notable as anything other than an efficient way for your body to dispose of T4.
When Thyroids Go Wrong
Your thyroid normally creates just the right amount of hormones for your body’s current needs, keeping all your cells active and operating smoothly. If your thyroid becomes defective, though, you’ll probably experience a bewildering set of disparate ailments because of the thyroid’s pervasive impact on all parts of the body. (For details, see Chapter 2.)
The three diseases that most frequently affect the thyroid are hypothyroidism, hyperthyroidism, and thyroid cancer. There are also a number of diseases that are less common or affect the thyroid indirectly.
Hypothyroidism
If you’re hypothyroid, your thyroid is underperforming— essentially, not making enough T4 and/or T3. This is by far the most common of all thyroid diseases, comprising over 80 percent of thyroid cases.
When your body doesn’t have enough thyroid hormones, the mitochondria in your cells will reduce their conversion of glucose into ATP. The unused glucose will be stored in your body as fat, causing you to gain weight. You’ll also start feeling increasingly tired as your energy supply winds down.
In addition, your body cutting down on the generation of new cells may cause your nails to grow dry and brittle, your skin to become rough and thin, and your hair to thin and fall out. At the same time, the lowered brain activity may make you confused, forgetful, and even dangerously depressed.
You can experience any of these symptoms, and/or dozens of others, because the “energy slowdown” caused by your underperforming thyroid will have different effects on different parts of your body.
Hypothyroidism is a complicated disease. With the help of this book, however, the chances are high that you’ll be able to navigate the various difficulties and obtain treatment that resolves all your thyroid problems. To find out much more, see Chapters 5 through 9.
Definition
Hypothyroidism is by far the most common of thyroid diseases. It’s caused by your thyroid underproducing its hormones, which reduces your energy and impairs the function of cells throughout your body. This can result in numerous ailments, ranging from the relatively trivial (brittle nails) to the devastating (severe depression). Fortunately, once it’s correctly diagnosed, hypothyroidism is highly treatable.
Hyperthyroidism
If you’re hyperthyroid, your thyroid is overperforming—essentially, making too much T4 and/or T3. This accounts for roughly 15 percent of thyroid cases.
When your body has an overabundance of thyroid hormones, the mitochondria in your cells will turn glucose into ATP at a much faster pace than normal. Once the available glucose runs out, your body will start turning your fat cells into glucose to keep up with the mitochondria’s demand for more fuel, causing you to lose weight. You might actually be happy about the latter. However, you’ll also start feeling increasingly manic from the extra energy.
You may also feel exceptionally anxious, nervous, irritable, or “shaky,” and experience panic attacks. In addition, your heart rate may increase to the point of pounding in your chest, which poses the risk of a heart attack.
Hyperthyroidism is a more dangerous disease than hypothyroidism, and it requires more complex treatment. However, in most cases it’s thoroughly manageable. For details, see Chapters 10 through 12.
Definition
Hyperthyroidism occurs when your thyroid overproduces its hormones, raising your body’s energy level beyond healthy limits. The overstimulation can cause such ills as tremors, severe anxiety, and a dangerously rapid heartbeat. Hyperthyroidism is treatable, but often requires time and patience until you either become healthy again or go in the other direction and become hypothyroid (which is a much easier disease to manage).
Thyroid Cancer
The thyroid disease that causes the most terror is thyroid cancer. It’s relatively rare, comprising about 1 percent of thyroid disease cases. It’s on the rise, however, with an increasingly greater number of people being struck every year.
Cancer has a reputation of being deadly and untreatable. Fortunately, that usually doesn’t apply to thyroid cancer, which is about as treatable as cancer gets. The most common thyroid cancers, papillary and follicular, have a cure rate of 97 percent. If you have thyroid cancer, your treatment will typically consist of surgically removing the thyroid, and then giving you a dose of radioactive iodine. Because your thyroid is the only part of your body that absorbs iodine, the iodine will be ignored by the rest of your body and enter only whatever thyroid cells remain post-surgery—including all the cancer cells—at which point the radiation will obliterate them.
For a detailed description of diagnosing and dealing with thyroid cancer, see Chapter 13.
Other Thyroid-Related Problems
There are a number of other things that can go wrong in your body that either affect your thyroid or are affected by your thyroid.
For example, your thyroid does its job in partnership with your adrenal glands, which facilitate the conversion of T4 to T3, and also allow T3 to enter cell membranes and access mitochondria. If your adrenals malfunction, lab tests will still show your thyroid to be working perfectly … because it is. But since your thyroid hormones are being blocked from doing their work, you’ll nonetheless be hypothyroid. To learn more about this subtle problem, see Chapter 14.
Other ailments that are in some way connected to your thyroid include parathyroid disease, thyroiditis, thyroid eye disease, and MEN syndrome. For details, see Chap-ter 15.
Two special problem areas resulting from thyroid disease that often don’t get enough attention are mental and emotional disorders, and women’s issues such as PMS, fertility, and menopause. These are covered in Chapters 16 and 17.
Why Thyroids Go Wrong
Thyroid disease is as old as mankind. In ancient times its primary cause was a lack of iodine. That’s no longer a serious issue in industrialized countries such as the United States, but a modern problem has taken its place: environmental toxins.
Your thyroid is extraordinarily effective at drawing in and storing iodine. That’s normally a good thing. However, there are a number of substances that are chemically similar to iodine, such as mercury and perchlorate. Small amounts of such chemicals may find their way into your body via processed foods, pesticides on produce, poor quality water, etc. If your thyroid mistakes them for iodine, it’ll suck them up and store them, too.
Over time, the amount of unhealthy chemicals that accumulate in your thyroid can become so significant that they’ll trigger your body’s immune system. Your body will designate them as foreign invaders, and create antibodies to attack them and flush them out of your system. Unfortunately, the antibodies will often mistake your thyroid as an accomplice of the toxins (which, in a way, it is) and also attack your thyroid cells.
This is called an autoimmune response; and it’s responsible for the vast majority of both hypothyroidism and hyperthyroidism. Experts believe this is why thyroid disease is so prevalent. Every year increasingly more chemicals are being pumped into both the environment and our food supply; and the older you get, the more toxins will accumulate in your thyroid.
That said, there are a number of things you can do to improve your chances of avoiding or mitigating thyroid disease. For numerous tips on how to avoid toxins, eat healthy, and live healthy, see Chapters 18 through 22.
One other problem in our modern age is low-level radiation, which is believed to be the primary cause of thyroid cancer (see Chapter 13). Complicating matters is that radiation is among the treatments for hyperthyroidism. For the pros and cons of pursuing this treatment, see Chapter 12.
The Least You Need to Know
- Thyroid disease has become an epidemic in the United States, striking 1 in 10 Americans.
- Your thyroid regulates the energy level of every cell in your body.
- Thyroid hormones are made from iodine, which you can get from eating iodized salt, seafood, and/or fresh vegetables.
- T4 is a “storage” hormone that your body converts to T3 when you need energy.
- The primary causes of thyroid disease in industrialized countries such as the United States are environmental toxins and low-level radiation.