Short answer: Graves' disease and Hashimoto's disease are both autoimmune conditions of your thyroid, and they usually push it in opposite directions. The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) says Graves' disease can cause hyperthyroidism, an overactive thyroid: your immune system makes an antibody called thyroid-stimulating immunoglobulin (TSI) that causes your thyroid to make too much thyroid hormone. In Hashimoto's disease, NIDDK says the immune system makes antibodies that attack the gland, and your thyroid becomes damaged and can't make enough thyroid hormones. That can cause hypothyroidism, an underactive thyroid, and only rarely an overactive one. The American Thyroid Association (ATA) calls Graves' the most common cause of hyperthyroidism in the United States, and Hashimoto's the most common cause of hypothyroidism. Doctors tell them apart with blood tests for TSH and thyroid hormones, antibody tests, and sometimes an uptake test or an ultrasound. Which one applies to you, if either, is your doctor's call.
If you've just seen one of these names on a lab order or a referral letter, it's easy to mix them up. Both are autoimmune. Both happen in the same small gland at the front of your neck. Both can come with a goiter. The difference is direction, and here it is side by side, with the US body behind each row.
Graves' and Hashimoto's, side by side
| Graves' disease | Hashimoto's disease | |
|---|---|---|
| What your immune system makes | An antibody called TSI that attaches to your thyroid cells and causes your thyroid to make too much thyroid hormone (NIDDK). The ATA also names TRAb | Antibodies that attack your thyroid. White blood cells build up there, and the gland becomes damaged (NIDDK). The ATA names TPO and Tg antibodies |
| Which direction | Hyperthyroidism, an overactive thyroid. NIDDK says many of your body's functions speed up | Hypothyroidism, an underactive thyroid, and rarely an overactive one (NIDDK) |
| How common as a cause in the US | The most common cause of hyperthyroidism (ATA). NIDDK puts it at about 4 out of 5 cases | The most common cause of hypothyroidism (ATA and NIDDK) |
| Symptoms the bodies list | Weight loss despite an increased appetite, a rapid or irregular heartbeat, nervousness, trouble sleeping, shaky hands, trouble tolerating heat, frequent bowel movements (NIDDK) | Often none at first. Then fatigue, weight gain, trouble tolerating cold, joint and muscle pain, constipation, dry skin or dry, thinning hair, heavy or irregular periods (NIDDK) |
| Tests the bodies name | TSH, T4 and T3; TSI or TRAb antibodies; a radioactive iodine uptake test, a thyroid scan, or a Doppler ultrasound (ATA and NIDDK) | TSH, T4 and T3; TPO antibodies; an ultrasound if antibodies aren't found (NIDDK) |
| Beyond your thyroid | More than 1 in 3 people with Graves' develop an eye disease called Graves' ophthalmopathy (NIDDK). Rarely, NIDDK adds, a skin change on the shins | A goiter that may feel like fullness in your throat, usually not painful (NIDDK) |
| Women and men | 7 to 8 times more common in women than men (ATA) | 4 to 10 times more common in women than men (NIDDK) |
The symptom row is where the two blur. The Cleveland Clinic says fatigue, muscle weakness, mood changes and irregular periods can turn up in both an underactive and an overactive thyroid. So it's worth writing down which ones you have, and when they started.
Osmi's daily check-in takes about a minute: you answer seven questions, or you speak with Rose, your thyroid mascot. Talk to Rose opens with one question, "How was today?", and you tell her in your own words. You answer, she files it on your dated record, the same record as your labs, cycle, and sleep. Osmi never diagnoses, treats, or prescribes.
What each one does to your thyroid
There are two things to hold apart here: what your immune system makes, and what that does to how much hormone your thyroid puts out.
Graves' disease. Normally your pituitary gland sends TSH to your thyroid. NIDDK describes TSH as "a hormone made in your pituitary gland that tells your thyroid how much thyroid hormone to make." Think of it as the note left on the fridge saying how much to cook. In Graves', NIDDK says, TSI "acts like thyroid-stimulating hormone (TSH)", so your thyroid gets a second set of notes it didn't ask for. The ATA puts the result plainly: "The antibodies in Graves’ disease bind to receptors on the surface of thyroid cells and stimulate those cells to overproduce and release thyroid hormones." NIDDK adds that symptoms "can come and go over time."
Hashimoto's disease. NIDDK says that in Hashimoto's "the immune system makes antibodies that attack the thyroid gland", white blood cells build up in it, and "the thyroid becomes damaged and can’t make enough thyroid hormones". The ATA names the antibodies: thyroid peroxidase (TPO) and thyroglobulin (Tg). It also says Hashimoto's "often progresses very slowly over many years", and that you may not have any symptoms early on, even if thyroid antibodies are detected in your blood tests. For what each of those antibody tests checks, see thyroid antibodies, explained.
So the split is plain. In Graves', the antibody pushes your thyroid to make more. In Hashimoto's, the antibodies attack it, and NIDDK says that can cause it to make too little.
Hypo versus hyperthyroidism: the two directions
Hypothyroidism and hyperthyroidism are the two directions; Hashimoto's and Graves' are the most common causes of each. NIDDK defines hyperthyroidism as when your thyroid "makes more thyroid hormones than your body needs", and says that with too much thyroid hormone, many of your body's functions speed up. Hypothyroidism is the opposite: without enough thyroid hormones, NIDDK says, many of your body's functions slow down.
NIH MedlinePlus Magazine lays the two side by side and starts with what they share: "Both can be caused by autoimmune diseases".
- Hypothyroidism (your thyroid doesn't make enough thyroid hormone): "May cause weight gain, constipation, slowed heart rate, dry skin and hair, sensitivity to cold".
- Hyperthyroidism (your thyroid makes too much): "May cause weight loss, nervousness, frequent bowel movements, sensitivity to heat, and muscle weakness".
- Both: "Symptoms like fatigue and an enlarged thyroid, also called a goiter, which may make your neck look swollen".
Graves' and Hashimoto's aren't the only causes. NIDDK lists overactive thyroid nodules and thyroiditis, an inflammation of the thyroid, among the causes of an overactive thyroid, and says that in some cases, after your thyroid is overactive for a period of time, it may become underactive. One type NIDDK names is postpartum thyroiditis, which can develop after giving birth. If that's your situation, see postpartum thyroiditis: what to write down.
And symptoms alone can't settle it. NIDDK says a hyperthyroidism diagnosis can't be based on symptoms alone, because many of its symptoms are the same as those of other diseases, and it says the same about hypothyroidism. It also says many of these symptoms, especially fatigue and weight gain, are common and don't necessarily point to a thyroid problem.
Your symptoms tell you something is worth asking about. The tests tell the two apart.
The tests doctors use to tell them apart
TSH first. The ATA says: "The best way to initially test thyroid function is to measure the TSH level in a blood sample." It says a high TSH level indicates the thyroid isn't making enough thyroid hormone, and a low TSH level usually indicates the thyroid is making too much. Those are the ATA's general patterns. Your doctor reads your own results against the range your lab printed, alongside your T4 and T3.
Antibodies next. The ATA says that in many people with an underactive or overactive thyroid, the immune system makes antibodies against the thyroid, and that "Measuring levels of thyroid antibodies may help diagnose the cause of the thyroid problem."
- For Graves', the ATA says: "Measurement of antibodies, such as TRAb or TSI, is cost effective and if positive, confirms the diagnosis of Graves’ disease without further testing needed." It adds that the test can be negative in some people with Graves', and then your doctor should refer you for a radioactive iodine uptake test. NIDDK also lists a thyroid scan, and a Doppler ultrasound, which your doctor may order "if radioactive iodine uptake is not a good option for you, such as during pregnancy or breastfeeding."
- For Hashimoto's, NIDDK names TPO antibodies, "a type of thyroid antibody that is present in most people with Hashimoto’s disease", and says: "You probably won’t need other tests to confirm you have Hashimoto’s disease." If your doctor suspects Hashimoto's but you don't have antithyroid antibodies, NIDDK says you may have an ultrasound. The ATA says an ultrasound may or may not be needed.
When the results come back, Osmi's lab album keeps them. Photograph the paper, upload the PDF, or type one number. Osmi files every result with its unit, date, lab and printed range, and a re-draw stacks on the same card and shows what moved.
Treatment is its own conversation, and it differs between the two. NIDDK says hyperthyroidism is usually treated with medicines, radioiodine therapy, or thyroid surgery, and that "Your doctor can help you identify the best option based on your age, health, symptoms, and other factors." For Hashimoto's, NIDDK says treatment usually depends on whether your thyroid is damaged enough to cause hypothyroidism, and that if it isn't, your doctor may simply check your symptoms and thyroid hormone levels regularly.
When to call your doctor
If you recognize yourself in either column of the table, that's enough to bring it up. NIDDK says symptoms alone can't make the diagnosis, which is why your doctor may use several blood and imaging tests to confirm it and find its cause. You're allowed to ask about them.
Two more things to mention. The Cleveland Clinic says it's important to share any family history of thyroid conditions with your provider, and NIDDK lists a family history of Graves' or Hashimoto's as something that makes Graves' more likely. And if your eyes are involved, the ATA says: "Patients who have any suggestion of eye symptoms should seek an evaluation with an eye doctor (an ophthalmologist) as well as their endocrinologist."
If your heart is racing or skipping and you also feel faint, have chest pain, or can't catch your breath, get urgent care rather than waiting for an appointment.
Questions to take with you
- Is my thyroid making too much hormone, too little, or the right amount?
- Which antibodies were tested: TPO, Tg, TSI or TRAb?
- Do I need an uptake test, a scan or an ultrasound, and what is each one for?
- If you're pregnant or breastfeeding: is this test safe for me?
- Should I see an eye doctor as well?
- How often should we recheck my levels?
- Can I have a copy of my results, with the ranges printed?
For the rest of what to bring, from your labs to the symptoms you keep forgetting to mention, see walk into your thyroid appointment with a real record. With Osmi's appointment sheet, you share your labs, trends, and daily record in one tap. It doesn't diagnose anything and it doesn't read your results for you.
Two names, two directions, one set of tests. Write down what you notice, and let the tests do the sorting.
Questions women ask about Graves' and Hashimoto's
Which is more serious, Graves' or Hashimoto's? There's no simple ranking. In a Cleveland Clinic article on an underactive versus an overactive thyroid, endocrinologist Mary Vouyiouklis Kellis, MD, says neither is necessarily worse, and the article adds that whether your thyroid makes too much or not enough, it can cause problems. NIDDK says untreated Graves' disease "can cause serious health problems", including heart rhythm and bone problems, and that untreated hypothyroidism "can lead to several health problems", including high cholesterol and heart disease. Ask your doctor what matters most in your case.
Can you have Graves' and Hashimoto's at the same time? NIDDK's and the ATA's patient pages don't say whether you can have both at once. What NIDDK does say is that Hashimoto's can rarely, early in the course of the disease, release too much thyroid hormone into your blood and cause symptoms of hyperthyroidism, and that a family history of Graves' or Hashimoto's makes Graves' more likely. If you're wondering about both, ask your doctor which antibodies were tested and what they showed.
Is every overactive thyroid Graves' disease? No. NIDDK says Graves' causes about 4 out of 5 cases of hyperthyroidism in the US, and lists other causes, including overactive thyroid nodules and thyroiditis. The ATA says a positive TRAb or TSI test confirms Graves' without further testing, and that a radioactive iodine uptake test can confirm it when the antibody test is negative or unavailable. Your doctor works out the cause from those tests.
Does Hashimoto's always cause an underactive thyroid? Not always, and not right away. The ATA says you may not have any symptoms early on, even if thyroid antibodies are detected in your blood tests. NIDDK says many people have no symptoms at first, and that early in the disease it can rarely cause symptoms of an overactive thyroid. NIDDK also says that if you don't have hypothyroidism, your doctor may simply check your symptoms and thyroid hormone levels regularly.
How can you tell if you're hypothyroid or hyperthyroid? Not from symptoms alone. NIDDK says many symptoms of both are the same as those of other diseases, and the Cleveland Clinic lists fatigue, muscle weakness, mood changes and irregular periods as ones that can overlap. The ATA says the best first test is a TSH level in a blood sample. Your doctor reads it with your T4 and T3, against the range your lab printed.
Which antibody tests separate Graves' from Hashimoto's? For Graves', the ATA names TRAb and TSI, and NIDDK names TSI, an antibody that causes your thyroid to make too much thyroid hormone. For Hashimoto's, the ATA names TPO and Tg antibodies, and NIDDK says TPO antibodies are present in most people with Hashimoto's. Ask which ones were on your lab order.
Educational, not medical advice.
