We have more than 70 organs in our body.

So it’s not surprising to  hear about one and think, I have no idea what that thing is for. At least, until something goes  wrong with said mystery organ.

Because when we’re talking about the thyroid, changes to this tiny organ can have a huge  effect on your body, and your mind too. This guy has its little hands all  over a lot of bodily functions. And when something goes wrong with your  thyroid, it makes it everybody's problem.

So today we’re going to explore  this little master of chaos to figure out what it looks  like at its best and its worst, and to talk about what you  can do when it all goes wrong. [♪ INTRO] The thyroid is a tiny organ that  kinda looks like a butterfly wrapped around your windpipe. More specifically, it’s a  gland that secretes hormones, which are busy doing all things metabolism. Our metabolism is responsible for converting  all of our avocado toast and Doritos and everything else we eat into energy.

And I probably don’t have to  tell you why energy is important. But energy production is not a simple process, and neither is the thyroid's involvement in it. It all starts in the brain, at the hypothalamus.

The hypothalamus is the part of the brain  that tries to keep the body in homeostasis. It’s kind of vibe checking your body  to make sure everything is a-okay. In terms of metabolism, the hypothalamus  can help us feel hungry and by extension, tell our bodies that we  are in need of more energy.

It does this by making its own hormone, called thyrotropin-releasing hormone, or TRH. That TRH shoots down the pituitary  stalk, to its friend the pituitary gland, which is located at the base of the brain. Thyrotropin cells in the pituitary gland then  receive this signal and release their own little chemical messenger, thyroid  stimulating hormone, or TSH.

That TSH makes the short jaunt to your throat and tells the thyroid what  to do with its hormones. Kind of like a really  convoluted game of telephone. The thyroid makes two main hormones: T4 and T3, both of which  are called thyroid hormone.

Once the thyroid hormone levels are high enough, the hypothalamus gets that telephone  message back and stops making TRH, which means the pituitary stops making TSH, which tells the thyroid to stop making T3 and T4. It makes a lovely little feedback  loop when all is working correctly. But all this stuff doesn’t just  happen perfectly on its own.

For one thing, the thyroid needs one major  ingredient to even make thyroid hormone, and that ingredient is iodine. We’re going to get to what happens if your  thyroid doesn’t get enough iodine later, but in places with stuff like iodized table salt, most people get all the iodine they  need to keep our thyroids happy. But not getting enough iodine isn’t  the only problem a thyroid can face.

Just ask the millions of people in  the US who have a thyroid disorder. Thyroid disease, like the gland  itself, is really complicated, because there’s a lot of ways to  mess up this nice little system. Sometimes thyroid problems are  something you’re born with, and other times they develop as you age.

There are also risk factors that can make  you more likely to develop thyroid disease, such as a family history of thyroid  disease, having comorbid conditions like Type 1 diabetes, being older than 60,  or literally just assigned female at birth. And there’s more than one way  that a thyroid can be messed up. When the thyroid hormone levels are  too high, it’s called hyperthyroidism.

Too much thyroid hormone kicks  your metabolism into overdrive and causes your body to burn  through energy too fast. This can lead to symptoms  like weight loss, anxiety, persistent thirst, mood swings, and diarrhea. One common cause of hyperthyroidism  is called Graves’ disease, which is an autoimmune issue where  your immune system attacks the thyroid, which causes it to release  way too much thyroid hormone.

And on the other hand, if the  thyroid doesn’t make enough hormones, then it’s called hypothyroidism. Without enough thyroid hormone,  your metabolism won’t work as much as it needs to, and you won’t have enough energy. You may experience weight gain, depression,  tingling in the hands, and constipation.

And yes, your immune system can cause this, too. Hashimoto’s disease is an autoimmune disease that causes thyroid damage  and leads to hypothyroidism. But like I said, this group  of disorders is complicated, and with that comes varied  and overlapping symptoms.

Some of those include fatigue,  sensitivity to temperature, loss of libido, muscle weakness,  hair loss, fertility problems, and irregular periods, if you get those. And sometimes an overactive thyroid  can cause symptoms related to underactive thyroids, and vice versa,  making all of this even more confusing. Like, around 10% of people with  hyperthyroidism experience weight gain instead of weight loss, and plenty  of people with hypothyroidism experience diarrhea instead of constipation.

And with all of that going  on, it’s no surprise to hear that patients often suffer from  mental health problems as well, ranging from depression and anxiety  to mood swings or psychosis. There are also thyroid conditions somewhat  outside of the hyper and hypo binary. Thyroiditis, for example, is  general inflammation of the thyroid, and it can lead to either hyper or hypothyroidism.

And that brings us to the problems that  come up if you’re not getting enough iodine. Iodine deficiency can present  a lot like hypothyroidism. Since if your body doesn’t have enough  ingredients to make thyroid hormone, it’s not gonna be able to make enough  to run your metabolism at full speed.

And while places like the US  have easy access to iodized salt, over a third of the world’s population  doesn’t, which puts them at risk of developing thyroid disease from  chronically low levels of iodine. So getting enough is a big deal. On the other hand, overconsumption of iodine can sometimes mimic hyperthyroidism  in some people, as their thyroids just keep cranking out more and more  thyroid hormone with the extra supply.

All of this is to say, thyroid  diseases are complicated, with symptoms all over the board and  a variety of causes to choose from. And if thyroid disease is left untreated,  it could lead to heart problems, osteoporosis, pregnancy  complications, or even comas. So, in the spirit of avoiding all of that, let’s talk about diagnosing and treatment options.

First, someone with that smörgasbord of symptoms will probably have found themselves  in the doctor's office already. If they suspect thyroid issues,  your doctor can order a blood test, which looks at the amount of thyroid stimulating  hormone available from the pituitary. Other tests can also check T4 or T3  levels, thyroglobulin that would suggest inflammation, or for thyroid antibodies  that would suggest an autoimmune disease.

In the meantime, doctors can also use their  eyeballs for a visual exam of the thyroid. Having the patient look up and swallow helps them see signs of swelling that  could indicate a problem. Imaging studies like an ultrasound can  also help get a better look at things.

Once it’s been determined that  your thyroid isn’t doing so hot, the first step is usually medication. For hypothyroidism, you can take a  synthetic thyroid hormone replacement to make sure you have enough  of the hormone in your system to get all your body business done. For hyperthyroidism, this could  be an anti-thyroid medication to stop your thyroid from cranking  out all of those hormones.

Or they can even use radioactive iodine  to purposefully damage your thyroid so that it can’t make so much of the hormones. Since your thyroid is a  thirsty little iodine sponge, it takes up radioactive iodine just  as easily as it does the regular kind. The goal here is to damage  the thyroid just enough, so it isn’t able to overproduce  those hormones anymore.

In severe cases of hyperthyroidism, doctors might even recommend surgery to  remove part or even all of the thyroid. While that surgery typically  involves an incision in your throat immediately in front of the thyroid,  some patients can have the surgery done through a hole in their armpit,  to avoid having a visible scar. So there are treatment options out  there for whatever ails your thyroid.

It’s estimated that more than 12%  of the United States population will have some sort of thyroid  disease in their lifetime, and since iodine deficiency  is a major global health risk, that rate could be even higher for countries  without access to things like iodized salt. So if the thyroid was on your list of  mystery organs at the start of this video, hopefully that’s no longer the case. But if you have a problem with your thyroid, it may take a little detective  work to find the right solution.

That little guy is complicated. Thanks for watching this SciShow  episode, and an extra-big shout-out to our patrons over on Patreon  for supporting our channel. Our patrons make all of our content possible, and we couldn’t do things like learning  all about thyroids without you.

We think you’re great. [♪ OUTRO]