Your thyroid is one of the most important glands in your body. It's small and usually described as "butterfly-shaped", located at the base of your neck. It's one of the regulators of the endocrine system and is responsible for manufacturing hormones that control your metabolism.
As with many bodily systems, there are generally two ways it can cease working normally; becoming too active, or becoming underactive. These, identified by the prefixes hyper or hypo respectively, lead to a variety of different systemic diseases.
Hyperthyroidism
In hyperthyroidism, your thyroid gland is making too much of the hormone it produces. As your body processes this excess amount of hormones, you feel the effects of an over-active metabolism.
While "boosting your metabolism" is a broad goal for weight loss, the boost you get from an overactive thyroid is very much not something you want. Just take a look at the symptoms: restlessness, nervousness, racing heart, irritability, sweating, shaking, anxiety, insomnia, thin skin, brittle hair, and muscle weakness. Sure, weight loss can also be a symptom, but it's uncontrolled weight loss; you'll lose weight from fat and muscle, and you'll continue losing weight even beyond the level you wanted to attain.
The most common disease that affects the thyroid to make it overactive is Graves' Disease, which is an autoimmune disorder. With this disease, your immune system identifies the thyroid as a foreign body and attacks it. Your thyroid, in response, goes into overdrive. Graves' Disease is the root cause of roughly 70% of hyperthyroidism, which itself is present in perhaps 1% of women and fewer men.
Hypothyroidism
The opposite of hyperthyroidism is hypothyroidism, where your thyroid gland doesn't produce enough of its hormone. It's relatively common, affecting as many as 4.6% of people in the United States. Often times, the symptoms are mild enough that they aren't noticed clinically.
Hypothyroidism can be caused by a variety of different forms of damage or suppression of the thyroid. Radiation therapy, used for things like cancer treatment, can damage or suppress the thyroid. Surgery that removes the thyroid, of course, will lead to low levels of thyroid hormone in the body. As far as diseases are concerned, the most common is Hashimoto's Disease. Hashimoto's, like Graves', is an autoimmune disease.
The symptoms of hypothyroidism include fatigue, dry skin, cold sensitivity, memory problems, constipation, depression, weakness, a slow heart rate, and weight gain.
Testing Your Thyroid
Millions of people have some form or another of thyroid dysfunction. Millions more have minor thyroid dysfunction, but it's not prominent enough that they feel bad or think they should do anything about it. Many people experience some of the symptoms of thyroid dysfunction and never associate it with their thyroid at all.
Normally, the way you get your thyroid function tested is with a doctor's visit and a blood test. It's a simple process; you go in and visit your doctor, discuss concerns about thyroid levels, and ask for a blood test. The doctor will usually refer you to a blood lab or a phlebotomist for a blood draw, and your blood will be sent to a lab for testing.
Thyroid testing looks for a few different possibilities. It might simply check for the presence and levels of thyroid hormones, T4, and T3. They might also look for something called TSH, or Thyroid Stimulating Hormone. See, your thyroid doesn't just work on its own, it needs stimulation, and it gets that stimulation from TSH. TSH is produced in the pituitary gland. Sometimes, thyroid dysfunction is actually caused by pituitary dysfunction and can be a sign of a different disease.
Another test that a doctor can perform is the thyroid antibody test. Antibodies are a part of your immune system, created when your immune system encounters and fights off disease. You have antibodies for things like the flu and various strains of the cold you've encountered, as well as diseases like chickenpox and polio, which you have (likely) been vaccinated for. Antibodies are like the instruction manual that tells your immune system how to fight off that disease if it should be encountered in the future.
The thyroid antibody test looks for signs that your body has built antibodies for thyroid hormones or for the thyroid gland itself. This is a sure-fire sign that you have some level of autoimmune diseases such as Graves' or Hashimoto's.
There are also some imaging tests that can be performed on the thyroid, due to its close location to the surface. Ultrasound and CT imaging can be used to look for physical maladies of the thyroid, including nodules or cancer. This helps identify the cause of thyroid dysfunction if that dysfunction is noted.
All of this requires a doctor visit, if not several, as well as trips to blood labs, imaging clinics, and other offices. It may also involve something called a radioactive iodine test, which necessarily involves radioactivity for imaging. This isn't harmful radioactivity – the dose is lower than what you would get just eating a banana, generally – but some people don't want to risk it.
There's also the global pandemic to consider; going into a doctor's office right now is a risky venture. Telemedicine exists and can help, but you can't get your blood drawn via a Skype call, so there's only so much such a conference can do for you.
If you're concerned about an overactive or under-performing thyroid, there are some ways you can try to test it at home.
Method 1: Look for Symptoms
The first thing you can try if you're concerned about thyroid levels is looking for the symptoms that are common to either hypothyroidism or hyperthyroidism. To remind you, the symptoms are:
- Overactive thyroid: restlessness, nervousness, racing heart, irritability, sweating, shaking, anxiety, insomnia, thin skin, brittle hair, weight loss, and muscle weakness.
- Underactive thyroid: include fatigue, dry skin, cold sensitivity, memory problems, constipation, depression, weakness, a slow heart rate, and weight gain.
In order to look for these kinds of symptoms, you'll want to remove as many confounding variables as you can.
For example, if you're used to drinking a lot of coffee or taking caffeine pills every day, you should stop taking them for at least a week before looking for thyroid symptoms. Caffeine induces many of the same symptoms as an overactive thyroid because it does the same thing; stimulates your metabolism. You will also want to focus on getting plenty of restful sleep and relaxing as much as possible. Your goal is, essentially, to get yourself as close to baseline as possible.
It's entirely possible to suffer from the symptoms of a thyroid disorder without any actual disease of the thyroid.
Once you've returned yourself to baseline, look at how many of the symptoms listed above you have. Typically, you will have most of the symptoms of one category and few or none in the other. You may have fatigue with an overactive thyroid, but you're unlikely to have the depression, weakness, or weight gain, for example.
If you have a handful of the symptoms for one and none for the other, you might consider looking into other steps to test for a thyroid issue. If you have symptoms from both categories, you may certainly have something wrong with you, but it might not be your thyroid. Many of these symptoms – from fatigue to depression to restlessness – are general enough that they can have a thousand different causes, and identifying it just from the symptoms is going to be nearly impossible.
Essentially, you should use the symptoms list as a filter; if you have enough of them to think you have a thyroid issue, you can carry on with other tests. If you don't, look elsewhere; for nutritional deficiencies, poor quality diet, lack of exercise, or a different kind of disease. Ultimately
Method 2: Perform a Physical Exam
The second test you can perform at home is a simple physical exam. For this, you will need both a mirror you can use to see your neck and a small glass of water.
Position yourself in front of the mirror where you can see the lower area of your neck, specifically the front of your neck. You're looking for the area above the collarbone but below the voice box. You can find various diagrams of the location of the thyroid online, like this one.
Focus on looking at this area of your neck, and tilt your head back. This puts tension on the skin in the area and makes anything under the skin more visible.
With your head tilted up and while watching that area of your throat, take a sip of water. You're looking for the moment when you swallow. What you're looking for are any bumps, protrusions, or odd shapes moving. A small symmetrical lump moving is fine; that's your thyroid naturally shifting as you swallow. You're looking for anything odd about it, like a lump sticking out. Something that protrudes to the side on one side of your throat but not the other, that kind of thing.
This is generally quite rare. A protrusion means you might have some kind of cancer, a cystic condition, nodules, or another physical malformation of your thyroid gland. This is definitely a case where you need to see a doctor, so call your physician immediately to make an appointment for an evaluation.
Note that you may still have a thyroid condition even if you don't see a physical malformation. Autoimmune diseases will not have a physical effect and tend to be much more common than a physical defect. This is simply a check to make sure you don't have something physically wrong in your throat.
Method 3: Overview Your Diet
Your thyroid uses the chemical iodine to produce its hormone. Iodine is important for your health, obviously, so if your diet doesn't have enough iodine in it, you may experience hypothyroidism.
If you have symptoms of a hyperactive thyroid, you will not have an iodine deficiency. This only applies if you have an under-active thyroid or the symptoms thereof.
Iodine deficiency was a problem for a while in the past, but it was largely solved through table salt. Most modern table salt is iodized, meaning that iodine is added to it. People don't use all that much table salt, all things considered, so there's no risk of iodine overdose. You would need to consume several grams of iodine to experience the effects of iodine poisoning, so unless you're just habitually drinking iodine, you won't have to worry about getting too much of it in your diet.
Getting too little iodine might be a concern for people pursuing particular kinds of diet. Since one of the main sources of dietary iodine is salt, if you're used to buying non-iodized salts instead of normal iodized table salt, you might be putting yourself at risk.
So, think about your diet. Are you getting enough iodized table salt? If not, don't worry yet; there are other natural sources of iodine you may be getting as well. Foods rich in iodine include seaweed foods like kelp, nori, and wakame, fish like tuna and cod, dairy products like yogurt and cottage cheese, and eggs.
Method 4: Buy a Kit
We live in a world where at-home genetics tests exist, so why not blood tests? Indeed, there are several forms of at-home test you can buy. These tests will mail you a kit with instructions on how to take a sample, which means drawing your own blood. You then mail this sample back to the company, where they test it for thyroid levels the same way a lab would test. 
Some examples of these kits include:
- This kit from Paloma Health. It costs $99 and tests T3, T4, TSH, and TPO markers.
- This kit from Everlywell. It costs $159 ad tests TSH, T3, T4, and thyroid antibodies.
- These kits from LetsGetChecked. One costs $99 and tests TSH, T3, and T4, and the other costs $119 and tests those plus antibodies.
The choice is yours; there are other companies selling similar kits, but they will all generally cost around the same amount of money and test the same things. You simply need to find a company you trust.
Method 5: See a Doctor
Other than a medical test, pretty much every method you have for diagnosing a thyroid condition at home is unlikely to be definitive. You'll still want to do a blood test and follow up with your physician, regardless of the results of a self-examination or compilation of your symptoms. Sometimes, things can't be easily done at home. All you can do is rule out certain indicators of a thyroid issue.
